Karmin Hello is the title track from the pop duo's debut album. Difficult slang English, get ready ;)

I'mma do it, do it
Like I wanna do it
You don't know me like you ain't never know me before
I'mma bring it, bring it
I'mma give it, give it
You gon' love me like you ain't love nobody before

Hello, Hello, Hello, Hello
Hello, Hello, Hello, Hello
Hello, Hello, Hello, Hello

You gon' love me like you ain't love nobody before
Too nice, too clean
Too white, too green
Little haters, big dreams
I don't care what you think about me
Two faced, old friends, told me, the end was near, forget them
See a lot of things changed since then
Don't they know that I came from Nebraska
Am I gonna quit? nice of you to ask
But momma told me go and chase what you after
I'm on track, so I'm gonna rap faster
I will break it down for you and get a lil' diva
Slaying on a prayer, on the record grim reaper
Running on thermometer, and yep I got a fever
Hi konichiwa, are you a believer?

I'mma do it, do it
Like I wanna do it
You don't know me like you ain't never know me before
I'mma bring it, bring it
I'mma give it, give it
You gon' love me like you ain't love nobody before

Hello, Hello, Hello, Hello
Hello, Hello, Hello, Hello
Hello, Hello, Hello, Hello

You gon' love me like you ain't love nobody before

Too hard, too soft, too rough, too posh
Lemme know what I want
Lace it up, baby tighter than nutter
Raise track, two legs, Hollywood, big break
Suck it up, intake
Let me tell ya how it happened real quick
Touchdown in the middle of the city
Massive street, jammed up to new weary
Know you done a party
Now tell me who you wearing
Loads of new hair held high you can carry
I'mma break it down for you and get a lil' diva
Slaying on a prayer, on the record grim reaper
Running on thermometer, and yep I got a fever
Hi konichiwa, very nice to meet ya

I'mma do it, do it
Like I wanna do it
You don't know me like, you ain't never know me before
I'mma bring it, bring it
I'mma give it, give it
You gon' love me like you ain't love nobody before

Hello, Hello, Hello, Hello
Hello, Hello, Hello, Hello
Hello, Hello, Hello, Hello

You gon' love me like you ain't love nobody before

Lemme keep going, baby till I'm dead and gone
That's my only wish
And if you don't know I'll be singing my song
I got a lot to give

I'mma do it, do it
Like I wanna do it
You don't know me like you ain't never know me before
I'mma bring it, bring it
I'mma give it, give it
You gon' love me like you ain't love nobody before

Hello, Hello, Hello, Hello
Hello, Hello, Hello, Hello
Hello, Hello, Hello, Hello

You gon' love me like you ain't love nobody before

I'MMA DO IT= (slang) I'm going to do it.

WANNA= (coll.) Want to.

YOU AIN'T NEVER KNOW ME= (slang) You have never known me.
Here we have a double negative (ain't + never) which is incorrect in standard English.
AIN'T is the negative form of the verbs TO BE or HAVE in the present simple.

YOU GON' LOVE ME= (slang) You're going to love me.

HATERS= People who hate other people or criticize them strongly.

TWO FACED= (adjective) A person who is not honest and trustworthy.

GONNA= (coll.) Going to.

LIL'= (coll.) Little.

YEP= (coll.) Yes, yeah.

LEMME= (coll.) Let me.

YA= (coll.) You.