Can you tell me how it is positive or negative with an example?
Pick two points on a line and then consider the leftmost point as your “first point” and the other one as your “second point”. If you have to go up from your first point to reach the second point then it has a positive slope; similarly, if you have to go down from your left point then you’re dealing with a negative slope. Finally, if your first and second point lies on the same “level” (no up or down) then the slope is 0.