Okay kiddo, so you know when someone does something bad or breaks the law they might have to go to timeout? Well, sometimes people do really bad things and they have to go to a special time out called prison.
His Majesty's Prison Service is the group of people in charge of making sure the prisoners stay in their timeout and follow the rules while they're there. They have guards and other workers who watch over the prisoners and make sure they're safe.
Prisons have lots of rules and schedules that prisoners have to follow. They have to eat at certain times, exercise, and sleep in their own little beds. Sometimes, they might get to do things like watch TV or play games, but it all has to be approved by the prison workers.
The goal of his Majesty's Prison Service is to make sure that the prisoners learn from their mistakes while they're in timeout so they can come out and be better people. They might also have to do things like apologize to people they hurt or pay back things they stole.
It's important to remember that not everyone who goes to prison is a bad person forever. Sometimes good people make bad choices and need to learn from them. That's why his Majesty's Prison Service is there to help them.