Assuming that you mean something like "This product hit the market last year", it means that it's now available for purchase. It is also common to say "it hit the shelves". Another possible meaning is "let's go to the market" if you said "let's hit the market" because it's often used for starting something or going somewhere. It's best to give an example sentence when asking about the meaning of a word or a phrase, because there are always many ways to interpret it out of context. Hit has many uses: - hit the beach (go to the beach) - hit the hay (go to sleep) - hit the can (go to the bathroom) - hit it (get started) - hit the road (get going) - want to hit that (slang for wanting to have sex with someone) - hit on someone (flirt, make passes at someone) - hit the jackpot (win a large amount of money or receive something to do with success, even have a relationship with a person who is better than you in some way) - hit rock bottom (be at your worst point, often used for addictions or mental states) - hit the books (study hard) There are so many others but I have to hit the road now!

Its an informal way to say that something for example a new item has become available for people to buy.

"hit the market" could also mean go to the market. For example; We were bored so we decided to hit the market.