There is no way to directly convert cubic yards to square yards. They are different types of units; cubic yards are a measure of volume, whereas square yards are a measure of area.
Units of volume do not directly convert to units of area. However, it is possible to find the number of cubic yards that fit in a square yard if the square yard has depth. The number of cubic yards that fit in such an area is the same number as the square yard's depth in yards. For example, if a square yard has a depth of 6 inches, which corresponds to a depth of 1/6 of a yard, then the number of cubic yards that fits in the space is 1/6.