Okay kiddo, so military drums are big round things that people hit with sticks to make loud noises. They used to be really important for armies a long time ago because they didn't have phones or radios to tell everyone what to do.
The drummers would play different rhythms to tell people things like when to march forward, or when to attack. They would also play music to make soldiers feel brave or to lift their spirits.
Nowadays, we still use military drums for things like parades or ceremonies. They're really loud and they make everyone feel really good!