Okay kiddo, let me explain what comitatus means in the context of the Kingdom of Hungary.
So, a long time ago, Hungary was divided into different regions called comitatus (pronounced "co-mee-tah-tus"). Each comitatus had its own leader, called a comes (pronounced "co-mez"), who was sort of like a governor.
The comes was responsible for making sure everything in their comitatus was running smoothly. They also had to provide soldiers and supplies to the king if he needed them for something.
The Kingdom of Hungary was a pretty big place, so having these leaders in each comitatus helped the king rule more effectively. It also helped him keep track of what was going on in each part of the kingdom.
So, comitatus is just a fancy word for a region or county in Hungary, and comes is the guy who was in charge of it. Does that make sense to you, kiddo?