There is no such shape.
A cube or a rectangular prism.
The question is somewhat confused. It has "... 6 flat SQUARE faces 2 are SQUARE and 4 are RECTANGLES ...." Assuming the first part is wrong, the shape is a cuboid.
5 Flat surfaces 4 flat surfaces (3 for the sides and 1 for the base).
A triangular based pyramid would fit the given description.
squares and rectangles
There is no 3D shape with 6 faces: 4 rectangles and 2 triangles. See the link for all forms of hexahedra.