Ok, so you know how the Pope is like the leader of all the Catholic people in the world, right? Well, sometimes he holds big special church services called masses where lots and lots of people come to see him and hear him talk about God and stuff.
During a papal mass, the Pope sits up front at a big, fancy altar and wears special clothes that are super pretty and holy. He has lots of helpers around him, like priests and bishops, who help with the service.
Everyone sings songs and prays together, and there might be some readings from the Bible. At one point, the Pope even gives a special blessing to everyone who is there, which is like a prayer for them to be happy and healthy and safe.
It's a really special and important time for Catholics to come together and worship as one big family, and people come from all over the world to be a part of it.