Okay kiddo, so when we talk about "acceptable level of violence" we mean how much violence is okay for people to do. Just like how you know that hitting your friend is not okay, we adults also have rules about this. These rules are different in different places and situations.
For example, if you play a game of tag with your friends, you might accidentally push someone or bump into them and that's okay because it's just part of the game. But if you were to purposely hit your friend and hurt them, that wouldn't be acceptable.
Now, when it comes to grown-ups, they also have their own rules when it comes to violence - like what is okay in sports or self-defense, and what is not okay in public or at home.
It's important for people to remember that hurting others is not good and that there are always consequences for our actions. And as we grow up, we learn more about these rules and what is considered acceptable and what is not.