The number of possible outcomes you are able to distinguish. For the cat, if the only information you get is dead/alive, two. If the probabilities aren't 50/50, you can think of one of those branches as stronger.
(Edited several times, this is the final version, I hope.)
How many universes "branch off" from a "quantum event", and in how many of them is the cat dead vs alive, and what about non-50/50 scenarios, and please answer so that a physics dummy can maybe kind of understand?
(Is it just 1 with the live cat and 1 with the dead one?)