Okay, imagine you're playing with your friends and you’re having fun. Suddenly, someone comes and starts making fun of you, calling you names, and saying mean things to you.
Well, that's what a troll is. It's someone who purposefully behaves badly and tries to upset other people, just for the sake of it. They might say things that are not true, mean, or hurtful. Basically, a troll is a person who likes to be mean to others online.
It's important to remember that trolls might be saying these mean things just because they think it's funny, or because they're bored. But remember, it's not okay to be mean to others, and we should always be kind and respectful online.