Alright, lets get started.
We have given that volume of cube depends on the lenght of side.
In cube we know that each side is of similar size.
Suppose the side lenght of cube is a, the volume of that cube will be a^3.
We have given in question notation of volume V(s).
V(3) = 27
Which shows the lenght of side of cube is 3 and the volume of cube is 27, which satisfies the formula also.
3 ^3 = 27 the volume given
So, the best interpretation of V(3) = 27 is the lenght of the cube side is 3 and the volume of the cube is 27. : Answer
Hope it will help :)