A cube has a total of eight vertices, despite having six square faces that would all have four vertices of their own if pulled apart. A cube has six square faces that are joined not only at the sides, but at the vertices, essentially resulting in two squares that are joined by four lines, one at each corner.
A cube is the three dimensional extension of a square. A square is a two dimensional shape with four equal length sides and angles of 90 degrees. A cube is a six-faced shape in three dimensions consisting of all square faces. All 12 edges of a cube are of equal length and all internal angles are exactly 90 degrees.