Okay kiddo, so a busby is a hat that some soldiers wear on their heads. It's really fancy and has a fun furry thing on the top called a "pom-pom".
The busby was first worn by soldiers a long time ago in a country called Hungary. But now other countries like Britain and Canada also use them for their soldiers.
It's a special hat that only certain soldiers can wear, like the ones in the cavalry or the guards. They wear them on special occasions, like when they're marching in a parade or guarding a palace.
The busby is made out of special materials like rabbit fur, leather, and metal. It's designed to protect the soldier's head from the sun and from things that might hurt them in battle.
So that's what a busby is! A fancy and protective hat for important soldiers.