slope is x/y. It is simply a way to measure how steep a given line is relative to x and y. For example, a 45° line would give you a slop of 1, because at any point in the line you could draw a line parallel to the x axis, then draw one from the end of that line parallel to the y axis until it intersects with the line again and these two legs would be equal, giving you 1/1 or 1. As the line gets steeper, the y variable increases, and as it becomes more horizontal the x variable increases.

I have completely forgot what m represents.

Hope this hasn't been too basic... finding the slope of a point (each point on a curved line has a particular slope, the line itself does not have one) on a curved line is a bit more tricky. I could explain how to do it conceptually, but I can't remember what equations to use and where to plug what in to figure out what the slope of a given curved line is.