Okay kiddo, so incivility means not being nice to someone. You know how we always say "please" and "thank you" and are polite to our friends and family? Well, if we're not polite and we say mean things or do mean actions, that's called incivility.
It's important to be nice to people because it makes them feel good and it also makes us feel good too. When we're mean to someone, they might feel sad or hurt and that's not a good feeling. Plus, being mean can cause problems and arguments between people.
So, let's remember to always be kind and polite to others, even if we're upset or angry. That way, we'll all be happy and get along better!