Okay kiddo, so Frattini's argument is kind of like a puzzle that mathematicians use to understand how things work.
Imagine you have a big box filled with different objects. Some objects might be toys, some might be books, some might be crayons. Now, let's say you want to figure out how many different ways you can choose 3 objects from the box.
Frattini, the mathematician, came up with a way to solve this puzzle. He realized that you can break down the problem into smaller parts. First, you can think about how many ways you can choose 1 object from the box. Then, you can think about how many ways you can choose 2 objects from the box, but only if you're choosing your first object from the box in a special way.
Now, here's the tricky part: Frattini realized that if you add up all the ways you can choose 1 object and all the ways you can choose 2 objects using that special rule, you actually get the total number of ways you can choose 3 objects from the box!
So, basically, Frattini's argument helps mathematicians understand how to break down big problems into smaller, more manageable parts. It's a super important idea in math and has helped solve lots of other puzzles too!