how do آپ rate a pop کوئز question?

but اگلے to the سوال theres a bar that says 'easy, difficult,medium 'etc , so where does that come from?

Oh, that relates to what percentage of people got the سوال right. The سوال is "hard" if only a few people got it right, "medium" if the جوابات are spread, and "easy" if lots of people answered the سوال correctly.