A fist displayed in a position to punch someone, or to fist-bump another person.
Oncoming Fist emoji is one of the most famous hands emojis, which is used just like the same favorite friendly gesture used in real life — i.e., to greet a friend instead of saying "hello", to say goodbye, to congratulate them with something they have done well, to celebrate ✌ Victory, and all things like that. Very rare, it may be used in the context of fighting with someone and hate — but primarily by people from countries where the fist gesture is not famous.
Oncoming Fist was approved as part of Unicode 6.0 in 2010 under the name “Fisted Hand Sign” and added to Emoji 1.0 in 2015.
U+1F44A
? Fisted hand sign