Imagine you are playing a game where you are a superhero. Your superhero has some things he or she is really good at, like flying or fighting villains. But your superhero also has some things he or she is not so good at. Maybe your superhero gets really angry easily, or maybe he or she never wants to ask for help.
These things that your superhero is not so good at are called character flaws. They are things that make your superhero more like a real person. Everyone has things they are good at and things they are not so good at, and that's ok. It's important to remember that even superheroes have flaws too!