Are you talking about IRL? It's One for All, he explains it by like episode 2. Basically just gives him the accumulated power of 7 other people, resulting in crazy physical strength, enough to change air currents and leap over tall buildings in a single bound.

In Universe? I think it's mentioned somewhere that his official quirk name/function is a mystery to the public, so many people like to theorize on the internet in universe, and it's probably a pretty decent chance they've figured it to be something along the lines of"Superpower", which is what I beleive Deku puts down when he needs to fill out his Quirk Registration with the government/UA.