Thank you both for answering! It helped a lot for me.

Shane's answer is good. Shane, put your comment in as an answer and then Bunch can choose it and close this question. I would add that I often associate 'hit' in this context with the possibility that this is a drug (cannabis?) that is being smoked. But I don't think that is exclusively the case

This is a great question. "Hit" can be used as slang when smoking cigarettes (or anything else you can smoke.) If someone says "wanna hit this?" they are probably asking "do you want to smoke one puff of this?" Saying "want to smoke this?" is fine too but it sounds slightly more formal. Slang like "wanna hit this?" is appropriate when the environment is very casual. There are some other smoking slang words that come to mind, too. When you take a puff of a cigarette, you are "taking a drag." If you want to ask someone if they can give you a cigarette, you can say "can I bum a smoke?" If you want to ask someone if they will let you have one puff of their cigarette, you can say "can I bum a drag." I am from Chicago and this is pretty common slang. I don't know if this is the case in other English speaking parts of the word!