Seta

Okay, imagine you have a bunch of toys and you want to put them in groups. You put all the cars together, all the dolls together, and all the blocks together. Each group is like a seta.

Now, imagine you want to know how many toys you have in total. You count all the cars, then count all the dolls, then count all the blocks. When you add up all the individual groups, you get the total number of toys. This is like adding up all the sets in a seta.

So a seta basically means you have different groups (or sets) of things, and you can count how many things are in each individual group or add up all the groups to get a total number. It's just a fancy way of organizing things!