Another hit by gospel band MercyMe.

Who are we
That You would be mindful of us
What do You see
That’s worth looking our way

We are free
In ways that we never should be
Sweet release
From the grip of these chains

Like hinges straining from the weight
My heart no longer can keep from singing

All that is within me cries
For You alone be glorified
Emmanuel
God with us

My heart sings a brand new song
The debt is paid these chains are gone
Emmanuel
God with us

Lord You know
Our hearts don’t deserve Your glory
Still You show
A love we cannot afford

Like hinges straining from the weight
My heart no longer can keep from singing

All that is within me cries
For You alone be glorified
Emmanuel
God with us

My heart sings a brand new song
The debt is paid these chains are gone
Emmanuel
God with us

Such a tiny offering compared to Calvary
Nevertheless we lay it at Your feet

Such a tiny offering compared to Calvary
Nevertheless we laid it at Your feet

All that is within me cries
For You alone be glorified
Emmanuel
God with us

My heart sings a brand new song
My debt is paid these chains are gone
Emmanuel
God with us

The song simply expresses how much joy he feels for having God loving us even though we don't deserve it.

A prophecy written 7 centuries before Christ said, "Therefore the Lord himself will give you a sign. Behold, a virgin shall conceive and bear a son, and shall call his name Emmanuel" /ɪmænju:əl/ (Is 7:13-14). The word Emmanuel (or Immanuel) means "God with us", and we Christians believe the prophecy was fulfilled in Jesus, because Jesus is God and he came to be with us (in most prophecies names are often descriptive labels, not usually real proper names). In Isaiah 8:8, Canaan is called the land of Emmanuel, though in other passages it is termed the land or the inheritance of God, so that Emmanuel and God are identified. The Gospel of Matthew (1:22-23) expressly identifies the Emmanuel with Jesus the Messiah: All this took place to fulfil what the Lord had said through the prophet: "The virgin will be with child and will give birth to a son, and they will call him Immanuel, which means, 'God with us'."

When Jesus died on the cross, on the hill called Calvary, He made the supreme sacrifice (God dying for us), and so, that could compensate for all our sins and make us all free. That's what the song is talking about.