The volume of a square is v equals s to the fourth. the side of a square is 4x to the third, what is the volume of the square

note a square is a 2 dimensional figure and so cannot have volume.

However, the 3 dimensional solid you may mean is a cube and the volume of a cube is

V = s³ ( where s is the length of the side )

here s = 4x, hence

V = (4x)³ = 64x³