Okay kiddo, let me explain to you what a banovina is! A banovina is a region that is divided for the purpose of governing or administration. It's like dividing a big pie into smaller pieces!
In the case of banovinas, it's like dividing a country like Croatia into smaller regions that have their own governors or leaders to help run things. These regions are called banovinas after the Ban, who was a medieval ruler in Croatia.
Banovinas were used in Croatia between 1939 and 1941 before it became a part of Yugoslavia. They divided Croatia into nine regions that each had their own governor to help run things. It was a way to make sure that every part of the country was taken care of and had their voice heard.
Nowadays, Croatia is divided into 20 counties instead of banovinas, but the idea is still the same: divide the land into smaller pieces to make it easier to govern and take care of.