It would help if we could draw diagrams on these boards but we can't. The problem essentially tells you how to work it.
The problem states that "the cube root of the volume of a cube gives the length of one side of the cube."
a, find the side length of the cube and it tells yoy that the volume is V = 343 cm^3. So take the cube root. Do you know how to do that on your calculator. Punch in 343, hit the y^x key and type in .3333333. My calculator returns 7.0 and you can check that by 7x7x7 = 343. So the length of the side of the cube is 7.0 cm.
b. If the sides iare 7.0 cm, then the area of a face is length x width = 7 x 7 ?? square cm