v(s) = volume of cube for some side length s units
If s = 2, then we can replace s with 2 to go from v(s) to v(2)
So v(2) represents the volume of a cube when it has a side length of 2 units
Saying v(2) = 8 is the same as saying "if the side length is 2 units, then the volume of the cube is 8 cubic units"
