Rectangular prisms have eight vertices. They also have six faces and 12 edges. "Vertices" is the plural of "vertex," which is defined as the point where three or more faces come together to form a point or a corner, in terms of polyhedrons
A rectangular prism is defined as a polyhedron for which the top and bottom faces are congruent rectangles. All the other faces, called lateral faces, are also rectangles. Because all of the sides stand at right angles to the bases, it is also a type of right prism. A cube is a special type of right, rectangular prism, where all of the faces are congruent squares.