It can be used in different contexts such as referring to when something /someone is dumb, drunk, high, or someone does not feel well.
I drank so much at the party I was hit as fuck
To inhale marijuana out of a bong
Damn this song makes me wanna take a hit.
A hit is a dose in which is enough to get you high on Weed Ecstacy Cocaine Meth etc.
Alex: Ayy man know where I could get a hit
Sean: yea bro follow me
Wow did you see Kate being a hit with that guy?
You look like you can flirt, you are such a hit!
A sentence of imprisonment. (May be in months or years.)
Joe appeared before the parole commission and was given a twenty-four month hit.