Can someone explain this article in layman terms? I do not know any sort of quantum terminology, sorry.

Specifically I would like to know what this means:

The ESP is quite a mild assumption, and to me it seems like a necessary part of being able to think of the universe as consisting of separate pieces. If you can’t assign credences locally without knowing about the state of the whole universe, there’s no real sense in which the rest of the world is really separate from you.