I googled it and it seems to be a bunch of stuff about abstract sets. As someone who did ok in math at high school, I find it hard to understand why people are so obsessed with sets. They’re just collections of elements and should be very simple, right? So why do we need complicated equations to describe them?
The more abstract and general a theory is, the more different things it can be applied to. If you can figure out how to describe any problem in terms of sets, you immediately have all the theorems of ZFC at your disposal.