What do you mean by power of lens?

The ability of a lens to converge or diverge the light rays is known as power of lens. A convex lens of short focal length bends the light rays through large angles, by focusing them closer to the optical center. Opposite to this convex lens of more focal length bend the light rays through short angle. Concave lens of very short focal length causes high divergence than with the long focal length lens.

Numerically, Power of lens is inversely proportional to focal length which is in meters.