On a topographic map, what is shown by contour lines that are a) far apart, b) close together and c) almost touching?

On a topographic map, the contour lines follow a certain elevation across the terrain.  So here's what each of the things you mention would mean:

If the lines are far apart, that means that there is little or no slope in that area of the map.  When the lines are far apart it means that there's a long horizontal distance between places with different elevations.

By contrast, if the lines are close together, that means there is only a short distance between places with different elevations.  That means it's a steep slope.

If the lines are practically touching, that means it's a very steep slope -- maybe even vertical.

On the second link provided, scroll down to "Contour Lines."