Okay, so there's this person called the Roman Pontiff, and he's like the big boss of the Catholic Church. The Catholic Church is like a huge club where lots of people go to talk to God, learn about Jesus, and try to be really good people.
So, the Roman Pontiff gets to be the boss of the club because he's seen as the leader of all the other people in the club. He's like the captain of the ship, and everyone else follows his lead.
This idea is called the "primacy of the Roman Pontiff," which means that he's the most important guy in the whole club. In fact, some people believe that the Roman Pontiff has been appointed by God himself to be the leader of the Catholic Church!
So, whenever there's a big decision to be made in the club – like which rules to follow or who should be in charge of what – everyone looks to the Roman Pontiff for guidance. They trust him to make the right decisions and help everyone stay on the right path.
All in all, the primacy of the Roman Pontiff is just a fancy way of saying that the leader of the Catholic Church is super important and everyone should listen to what he says.