The base and the height are related to the area since in various figures, to calculate the area, these values must be known.
For example, in a rectangle:
The area of a rectangle is equal to the base of this by its height, that is:
a = b * h
The same case of the area of a triangle, is the height by the base, divided by two, that is:
a = b * h / 2
And there are more examples, which means that thanks to the base and height of an object we can calculate its area.