If we assume the length and width dimensions apply to the base, the area of the base is
A = l*w = (6 cm)*(8 cm) = 48 cm²
The volume is the product of the area of the base and the height.
V = Bh
V = (48 cm²)*(7 cm) = 336 cm³
The area of the base is 48 cm².
The volume of the prism is 336 cm³.