Slope describes the steepness of a line on the coordinate plane, whether it rises from bottom left to top right (positive slope), top left to bottom right (negative slope), or horizontally across (zero slope). Examples are given of objects that demonstrate each type of slope, such as roads that have positive slope as they go up hills, slides that have negative slope to go down, and shelves that have zero slope horizontally. Steeper slopes are closer to the y-axis, while flatter slopes are closer to the x-axis. Real-world examples like steep hills and flatter golf greens illustrate different degrees of positive and negative slope.