Youth justice in England and Wales means how kids who break the rules and laws are dealt with.
If a kid does something naughty, they will meet people called police officers. The police will decide if they need to go to court. If they do, they'll go to a court where the people in the court will try to find out if the kid did something wrong or not.
If they decide the kid did something bad, the kid will go to a place where other kids who have done wrong go. This place is called a youth detention center. There, they'll be helped to learn how to be good, do good things and avoid doing bad things.
The people who work in the center want to make sure the kids do things that are good for them and others. They make sure the kids have education and counseling. They also make sure the kids are safe, eat good food, and have a comfortable bed to sleep in.
The goal of youth justice in England and Wales is to help these kids become better people and to take responsibility for their actions, so they won't do anything bad again in the future.