The sign is not meaningless, and its meaning is as Magic Pickles interpreted it. It is common business practice to state one thing and then say "What it means is ..." when called on it. That does not change the statement, which should be better phrased.

In context ("Air France/KLM lounge primarily for Air France/KLM first class customers"), the sign's statement is strange at best, but that does not change what it says, and it says that Priority Pass members will be admitted.