Brehon was a type of judge who lived a long time ago in Ireland. They were very important because they helped people solve problems and decide what is right when there is a disagreement.
The Brehon had a special way of making decisions. They would listen to both sides of the argument and then they would look at a big book of laws called the Brehon Law. The Brehon Law had lots of rules about different things like how to take care of animals, how to share land, and how to behave in a fair way.
The Brehons were really smart and they knew all about the Brehon Law. They would use their brains to figure out what the correct decision was based on what the Brehon Law said.
So if you had a problem, like someone took your toy and won't give it back, you could go to the Brehon and they would help you figure out what to do. They would listen to your side of the story and the other person's side of the story and then decide what is fair based on the Brehon Law.
In summary, Brehon is like a super smart judge who lived a long time ago in Ireland and helped people solve problems in a fair way by using a special book called the Brehon Law.