More specifically, an artificially created world that supposedly mimics our own, only because each person plugged into it (as opposed to going through a backdoor like Daisy and I did) have their greatest regret erased so the world adapted to that decision which has led to Hydra being in charge. If the avatar of you dies in the Framework, you die in the real world. And those who have already died are now running around, apparently as figments of memory from those plugged in.