The number of edges in a cube is 12.
4 + 4 + 2 + 2 = 12
Edges in the bases (total of 8)
Then the another two on the left, then another two on the right (total of 4). It may serve as the height/distance of each bases..
You can try it on actual, a rectangular box (no. of edges on a rectangular solid and cube is just the same so it will do the trick).