A cube has 4 flat surfaces (called faces) and 6 vertices (or corners).
A cuboid.
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.
A triangular based pyramid would fit the given description.
5 Flat surfaces 4 flat surfaces (3 for the sides and 1 for the base).
A cube has 4 flat surfaces (called faces) and 6 vertices (or corners).
A cuboid.
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.
A square has 4 flat surfaces.
A triangular based pyramid would fit the given description.
5 Flat surfaces 4 flat surfaces (3 for the sides and 1 for the base).
There is no 3D shape with 6 faces: 4 rectangles and 2 triangles. See the link for all forms of hexahedra.
squares and rectangles
Cuboid
The solid figure that has 4 flat surfaces that are triangles is a tetrahedron. A tetrahedron is a polyhedron with four triangular faces, six straight edges, and four vertex corners. Each of the four faces of a tetrahedron is an equilateral triangle, making it a regular polyhedron.
You need 4 rectangles and two squares * * * * * No, you do not need to have squares: there can be six rectangles - as in a brick shape.