Okay kiddo, let's talk about nuncios. A nuncio is like a messenger boy, just like the one who brings you a message from your mom or dad. But nuncios are special messenger boys who work for the Pope, who is like the boss of Catholic religion.
Their job is to deliver important messages and instructions from the Pope to other people who work for the Catholic Church or to other important people in different parts of the world. They usually travel a lot and stay in different countries for a while to do their job.
Overall, a nuncio is an important messenger who helps the Pope communicate with other people who are important to the Catholic Church.