what does stars mean
If you come across an answer that you think awesome, you can give it a "helpful" star to show that community member that you appreciate their answer.
Also, if you think an answer doesn't actually answer but is still interesting, you can rate it as "Fun" to show the feedback is still appreciated. That's what I do.
People use it as a way to tell someone they agree with them or like the answer, whether it was actually helpful or not. I use 'fun' only when i think something is really funny.