Probably about as difficult to explain as Alpha Centauri Expeditions, the Avatar Program, and the Pandora Conservation Initiative . . . which is to say, not particularly, because they design the stuff to make enough sense that you can have fun on the ride whether you know all the particulars or not. It's background, it's atmosphere. The onus isn't on guests to parse a scientific journal before riding Flight of Passage, or even chart the events between Avatar the movie and the present moment in Pandora the land. That stuff's just there to color the experience generally for the uninitiated and offer some exposition, world-building, and lore for the initiated. Which is almost certainly what will be happening with this ride.
But if you want to give your kids an early primer, you can tell them that a Food Co-op is like a grocery store that's owned by the community.