Dear kiddo,
A barbette is a big hole in the middle of a battleship or a fort where a big gun sits. It's kind of like a huge metal straw sticking up out of the ship or fort. The gun is put inside the straw and it can move around and shoot in different directions.
So why do we have barbettes? Well, it's so that the warships and forts can protect themselves from enemy attacks. When the battle starts, the big gun in the barbette shoots out massive bullets that can destroy the enemy ships or weapons from far away.
It's like having a superpower on your side in a fight! The barbette is very important to the ship or the fort, and it needs to be strong and well-protected so that the gun inside can keep firing and protecting its crew.
I hope this helps you understand what a barbette is and why it's important. Just remember, it's like a big straw that holds a giant gun and makes the ship or fort powerful and mighty in a battle.