Okay kiddo, so the FBI cyber division is a group of really smart people who work for the FBI and specialize in catching bad guys who use computers to do bad things.
You know how you like to play games on a computer and watch videos on the internet? Well, some people use computers to steal things from other people, or to hack into important websites and mess them up. The FBI cyber division is in charge of stopping those bad guys from doing those things.
The people who work in the FBI cyber division are really good at using computers themselves. They know how to find clues and evidence on a computer that can help them catch the bad guys. They also work with other people and companies who are good at keeping the internet safe, so they can all work together to catch the bad guys and protect people like you and me who use the internet.
So basically, the FBI cyber division is like a team of superheroes who use their computer skills to keep the internet a safe place for everyone to use.