The lyrics are in the Hindi language.  Here are the original Hindi lyrics, followed by an English translation.

(This is a one-sided love song from the female point of view. She says that it's just a small matter of you not being present here (sarcastically), yes we are heartbroken, yes I have been on your shoulder imagining a dream. But since you are not here and you didn't even care. That's what this song is about.)

Baat Hai – Lyrics 
Intro 
Itni si baat hai 
BeeƟ jo raat hai 
Tumne nahi kabi jaana 
Itni si baat hai 
Wo jo na sath hai 
Tanha hai dill 
Ye deewana 
Verse 
Kande pe tere 
Sir yu rakh kr 
Sapna mene dekha tha 
Baato me teri khoi rahi hu 
Tumse dill ye ulja tha 
Itna ajeeb hai 
Dill jo ye kareeb hai 
Tumne nahi kahi jaana 
Toote jo hum hai 
Zara sa to gum hai 
Sunna hua aashiyaana 
Hook 
Itni si baat hai 
BeeƟ jo raat hai 
Tumne nahi kabi jaana 
Itni si baat hai 
Wo jo na sath hai 
Tanha hai dill 
Ye deewana X2 
Chrous 
Itni si baat hai 
BeeƟ jo raat hai 
Tumne nahi kabi jaana 
Itni si baat hai 
Wo jo na sath hai 
Tanha hai dill 
Ye deewana X2 
Tumne nahi kabi jaana 


ENGLISH


Intro
Such a small thing it is,
This night that is so long,
You never knew,
Such a small thing it is,
That which is not with me,
My heart is lonely,
It's crazy.

Verse
With your head resting on my shoulder,
I had seen a dream,
In your words, I got lost,
My heart was tangled with you,
It's so strange,
The heart that's so close,
You never said anything,
We who are broken,
There's a little sorrow,
This is what they say, a home that's been heard of.

Hook
Such a small thing it is,
This night that is so long,
You never knew,
Such a small thing it is,
That which is not with me,
My heart is lonely,
It's crazy.

Chorus
Such a small thing it is,
This night that is so long,
You never knew,
Such a small thing it is,
That which is not with me,
My heart is lonely,
It's crazy.
You never knew.