There is no such shape.
6 flat surfaces - known as faces, 12 edges 8 vertices.
A cube. Vertices are corners and a cube has 8 corners. Faces are the flat surfaces on three dimensional shapes a cube has 6 faces.
A triangular based pyramid would fit the given description.
A cube or cuboid have 6 flat surfaces and 8 vertices. (A cuboid means shaped like a cube - an example being a shoe box.)
It is a cube or a cuboid
A triangular prism.