It's one of those things that's hard to get for most of us not because we don't understand what it is, but that we don't understand what not having it is like. Most languages in common use have this.

It can be similarly difficult to explain to people what structured programming is, because basically everything is structured programming now. The hard part is understanding what non-structured programming is, so that you can then understand the contrasts, because there is so little experience with it anymore.