the estimated volume would 2 cubic yds
the volume of any pyramid is defined by V = (1/3)Bh where B is the area of the base of the pyramid and h is the height of the pyramid.
Here:
B = (.5)(3)(2) = 3 rounding the dimensions of the base
h = 2 rounded
So volume would be V = (1/3)(3)(2) = 2 cubic yds