This is called a hexagonal prism. Some 3D shapes, like cubes and pyramids, can be opened or unfolded along their edges to create a flat shape. The unfolded shape is called the net of the solid.

A 3D shape with all straight edges and flat faces is a polyhedron. Other 3D shapes with least one curved surface are not polyhedra. A 3D shape with regular polygonal faces, meeting at equal angles ...