please help me understand how it works!!

for my tax return I got the following:

Fed=$1,629

Ny=$662

1)where do this numbers come from?

I mean, I'm happy, but I just want to know in the future if I will get more or less and if so, how do I know.?

2)why am I getting a tax return,!? like who's fault is it?

I will give you a thumbs up, so please explain