A pole star is a focal point for character motivations and interactions. They are meant to encourage characters to have a reason to be together and interact, but they may also introduce tension or drama. Pole stars are things a character wants to do something about, or with. Pole stars aren't what your game is "about", but they can be if you want.
Characters will have a position toward a pole star. If you can say "I want to (something) this pole star", or "I am (something) about this pole star", that something is your character's position.