A more thorough explanation:

Boni homines were free tenants who judged each other in their lord's court.

In the past, when someone owned land, they were called a lord. The people who lived on the land were called tenants. If there was a problem between the tenants, the lord would ask some of them to be judges. These judges were called boni homines. They were chosen because they were good people who could be trusted to make fair decisions.

For example, if two tenants had a disagreement about who owned a piece of land, the lord would ask some boni homines to listen to both sides and decide who was right. The boni homines would talk to witnesses and look at any evidence before making their decision.