Okay kiddo, so Vatican City is a teeny tiny country that is run by the Pope, who is like the boss of the Catholic Church. Even though they are a small country, they still need some protection like other countries. So they have a special group of people called the Swiss Guard who are in charge of keeping them safe. They wear colorful uniforms that look a little like costumes and they carry big swords, but they also have more modern weapons like guns. Their job is to guard the Vatican and the Pope, and make sure everyone stays safe. So basically, the military in Vatican City is a small group of specially trained people who protect the Pope and the Vatican.