Okay kiddo, so imagine you have a bunch of big blocks, but these blocks can't just be stacked randomly. There are some rules you have to follow, like you have to put some blocks in a certain order before you can add another one.
In math, we call this a directed set. It's a set of things (like blocks), but they have a direction or an order that they need to be arranged in. This direction or order might be given by a function or a relation between the things in the set.
For example, let's say we have some numbers. We could put them in a set like {2, 4, 6, 8, 10}, but that's not directed. We need to pick a direction or order for them. Maybe we'll arrange them in ascending order, so the smallest number 2 comes first, and then we add the next smallest number, 4, and so on until we reach the biggest number, 10.
Another example could be a set of all the people in a line waiting for a ride. There's a direction to this set - the person at the front of the line will be the first one to get on the ride, and the person at the back will be the last one.
So a directed set is just a set where there's an order or direction to how the things in the set are arranged. And just like with those blocks, we always have to follow the rules of the directed set when we're adding or arranging things.