OK kiddo, so you know how the Vatican City is a tiny country inside Italy, right? Well, like any country, they have their own rules and people in charge to make sure everyone is safe and happy. That's where the military of Vatican City comes in.
The military of Vatican City is made up of two groups of people: the Swiss Guards and the Vatican City State Gendarmerie. The Swiss Guards are the most famous because they wear really cool uniforms that look like costumes from a play. They also have funny hats called "helmets" that have brightly-colored feathers sticking out of them. But don't be fooled by their fancy clothes, they are very serious about keeping the Vatican City safe. They are trained to protect the Pope and guard the entrances to the Vatican City.
The Vatican City State Gendarmerie are a bit like regular police officers. They patrol the streets of the Vatican City, make sure everyone is following the rules, and investigate crimes if necessary. They wear uniforms that are a bit more plain and modern than the Swiss Guards, but they still look pretty important.
Together, the Swiss Guards and the Vatican City State Gendarmerie make sure everyone in the Vatican City is safe and secure. So if you ever visit the Vatican City, you can rest assured that the military is there to keep you safe.