A light bounces off the surface of a metal cup and shines in Harold’s eyes?

The phenomenom that describes this behaviour of the light bouncing in a metal surface and shining in Harold's eyes is the Reflection of light.

Reflection is when light bounces off an object.

If the surface is smooth and shiny, like water, glass or polished metal, this light will reflect at the same angle as it hit the surface.

This kind of reflection is called specular reflection

The angle at which light hits a reflecting surface is called the angle of incidence and the angle at which light bounces off a reflecting surface is called the angle of reflection.

In the specular reflection each incident ray is reflected, with the reflective ray having the same angle to the surface normal as the incident ray.