What 3d shape has 12 edges and 6 faces?

Answer 1

You ask the question as if there were only one possible answer. This is not at all the case, but one example of such a shape is a cube. The unit cell of the triclinic crystal system is another, and there are even less symmetric possibilities (for example, there's nothing in your description requiring the opposite faces to be parallel), but I can't think of any simple name to give them.

Answer 2

to use your IQ to solve every problem