Okay kiddo, so let's say you have a big group of friends who love to play together. But sometimes, some of your friends might want to hang out in their own smaller group. That's kind of like a subgroup.
Now, the Kurosh Subgroup Theorem says that if you have a really big group, and you want to understand all of the subgroups inside of it, you can actually do that by looking at smaller groups and how they fit together.
It's like if you have a puzzle with a lot of pieces. You can try to figure out where each piece belongs on its own, or you can start by looking at smaller sections of the puzzle and then putting those sections together to solve the bigger puzzle.
So the Kurosh Subgroup Theorem is a way to solve that "big puzzle" of understanding all the subgroups of a really big group. It helps us break a big problem down into smaller, easier-to-solve problems.