What does Berkeley think we mean when we say "that table exists"?

You could say any of these without being wildly wrong, but I would say bottom left is the best. Answer 1 doesn't cover Berkeley's claim (at one point) that when you say such and such a table exists even though there is nobody perceiving the table what you mean then is that if someone was perceiving it certain experiences would be had (ie bottom left). Berkeley also says that a thing exists when mortals are not perceiving it in virtue of its being perceived by God (as celebrate by the famous Knox verses), so top right is not silly. It was Dr Johnson who thought he could show that Berkeley was silly by aggressively kicking the table (apparently thinking that if Berekeley were right his boot should encounter no resistence).