In December 2012 twenty-seven people were killed by a murderous loony in a school in Newtown, Connecticut; twenty of them were children aged 5-10 years old. The coaches and artists of "The Voice" pay tribute to the Connecticut shooting victims with Leonard Cohen's "Hallelujah".

I heard there was a secret chord
That David played, and it pleased the Lord
But you don't really care for music, do ya?
Well it goes like this
The fourth, the fifth
The minor fall and the major lift
The baffled king [composing] Hallelujah
Hallelujah
Hallelujah
Hallelujah
Hallelujah

I did my best and it wasn't much
I couldn't feel, so I tried to touch
I've told the truth, I didn't come to fool ya
And even though it all went wrong
I'll stand before the Lord of Song
With nothing on my tongue but Hallelujah
Hallelujah
Hallelujah
Hallelujah
Hallelujah

CHORD= /kɔ:*d/ This word used to refer to the strings of a stringed instrument, like a guitar or a harp. Today we use it to express a kind of melody created with those instruments (in this case, David's harp). In this song, A SECRET CHORD means "a secret melody (that David played with his harp)".

DAVID= A little young shepherd, born in Bethlehem. Still quite young, God chose him and he became King David, the second king of the Israelites and its most important king ever. He was also a great sinner and a great saint, the perfect example of how an incredible man can fall down and get up again, and fall down, and get up again and again. He was also a distant ancestor of Jesus and reigned around the year 1000 BC. He is the one who unified all the Israelite tribes in one single kingdom and set its capital in Jerusalem, turning this little town into the political and religious capital of Israel. He was also a great musician and composed many songs to praise God, many of them compiled in the Book of Psalms of the Bible and still sang today very often in Jewish and Christians religious services, 3,000 years later.
His most famous deed was when, still a young boy, he killed Goliath, a huge Philistine warrior, throwing him a stone with his sling.
His most terrible sin was when he fell in love with Bathsheba, a beautiful woman that he saw from his palace room when she was having a bath. He ordered his husband, Uriah, to be sent to the battle in a most dangerous position, so he was killed and he could marry her.
Still, every time he fell into sin, he turned back to God and claimed for his mercy, again and again, that's why God loved him so much, not because he was good and perfect, which he wasn't, but because David's repentance was even bigger than his sins.

IT PLEASED THE LORD= God liked it.

YOU DON'T CARE= You don't think it's important or interesting (or you don't have time for music now).

DO YA?= Do you?
The form "ya" /jə/ is a colloquial spelling to reflect the colloquial pronunciation of "you".
Question tags (, auxiliary + pronoun) are used at the end of a sentence when we need confirmation because we are not completely sure. When the sentence is affirmative the question tag is negative, when it's negative the question tag is affirmative:
+ - She's rich, isn't she? (= tell me yes or no, I'm not completely sure)
- + You don't like her, do you? (= I think you don't like her but I need confirmation)
But we can also use a question tag even when we are sure that what we said is correct. In that case, the intonation is not rising like in questions, but falling, and we use the question tag just to press the listener to say something, whatever.
- + You don't care, do you? [falling intonation] (= I know perfectly well that you don't care)
This second type of question tags is the one used here in this line ("but you don't really care for music, do ya?")

IT GOES LIKE THIS= This is how it sounds.

THE MINOR FALL...= The line "the fourth, the fifth, the minor fall and the major lift" has a double meaning. On the one hand it describes the melody using musical technical words. On the other hand, after mentioning King David, it's easy to think of this as a series of falls and repentances ("lift" is "elevate", get up, "minor" also means "not very important" and "major" means "very important"). Since this song is about love, this talks about problems or infidelities and subsequent repentances (to repent is to genuinely feel sorry about something wrong you did and to ask for forgiveness)

THE BAFFLED KING= A new reference to King David. BAFFLED means "confused, perplexed, that can't understand the situation". David was baffled because he couldn't understand why he was falling again and again when he wanted to be always good and perfect (but he was too weak). But in the context of this song, his bafflement is the result of a horrible massacre he just can't understand.

HALLELUJAH= (alternative spellings: Halleluyah, and the Latin form Alleluia ) A religious word of Hebrew origin meaning "praise be to God". It is used to praise God, and also to express great joy.

I DID MY BEST= I did it as good as I could.

FOOL= Deceive. If you fool someone you make them believe something which is not true.

This song only uses two paragraphs from the original song by Leonard Cohen, so the original story is lost and they turn it into a religous tribute in behalf of the people killed in the massacre, especially the children. It recreates the moment when all those innocent souls will stand before the Lord singing Hallelujah.

The biblical referece goes for King David, the most important king of ancient Israel, who had been a shepherd and a harp player and who reputedly composed most of the biblical psalms (songs of praise).

According to the resulting context here, David's songs of praise turn into a sad and sorrowful lament, and "the baffled king" (puzzled, confused) just can't understand the horror of what has happened, but still he praises and sings Hallelujah. In the second paragraph the king feels impotent and shocked, but in his sorrow, he stands before the Lord and sings Hallelujah.

An alternative interpretation in this context could be that in the second stanza it is the children who come before the Lord and sing in praise, so in either case, the song expressed the hope that in the middle of all that horror, the kids are now enjoying God's love in heaven.