A ban is a funny word that means a way to measure things. Just like how you can measure how tall you are with a ruler, we can measure really heavy things with a ban.
It's like a group of little guys that work together to see how heavy something is. They hold it up and say "this is 1 ban!" Then, they put something else on top and say "this is 2 bans!" And they keep adding things until they can't hold it anymore.
When we talk about bans, we usually talk about how much something weighs. So, if someone says something weighs 10 bans, we know it's pretty heavy!
But, we don't really use bans a lot anymore. We usually measure things in pounds or kilograms instead. But, it's still fun to learn about how people used to measure things a long time ago.