Okay kiddo, imagine you are playing with your toy cars. Let's say you have 100 cars. Now, if you group these cars into sets or groups of 10 cars each, you will end up with 10 groups of cars, right? Good job!
Now, imagine instead of toy cars, we're talking about people. Sotnia is a Ukrainian word that means a group of 100 people. This term became more widely known during the Ukrainian Revolution in 2014, when Ukrainians would group themselves together in sotnias to march and protest against the government.
So basically, a sotnia is just a group of 100 people who come together for a shared purpose. Just like how you and your friends might team up to play a game together, sotnias in Ukraine formed larger groups to make their voices heard and fight for what they believed in.