Imagine you have a bunch of toys, like toy cars or dolls. And you have a group of kids who want to play with the toys.
Normally, the kids would each pick one toy and play with it. But let's say you want to make it more interesting. You decide that each kid will get to play with two different toys.
Now, you might think that this is simple enough. But let's say one kid has already chosen a toy and another kid comes along and wants to play with the same toy. What do you do?
This is where 2-transitive group comes in. A 2-transitive group is like a set of rules that tell you how to choose which kid gets to play with which toy.
It's called 2-transitive because it has two levels of choosing. The first level is choosing the kids. The second level is choosing which toy each kid gets to play with.
But here's where it gets even more interesting. Let's say you have a lot of toys and a lot of kids. You can use the same set of rules to figure out which kid gets to play with which toy no matter how many toys or kids you have!
And that's what a 2-transitive group is. It's a set of rules that lets you choose which kid gets to play with which toy, no matter how many kids or toys you have.