Reflection in computer graphics is used to emulate reflective objects like mirrors and shiny surfaces.

Examples
Mirrors
Mirrors are usually almost 100% reflective.
Metallic Reflection
Normal, (non metallic), objects reflect light and colors in the original color of the object being reflected.
Metallic objects reflect lights and colors altered by the color of the metallic object itself.
Blurry Reflection
Many materials are imperfect reflectors, where the reflections are blurred to various degrees due to surface roughness that scatters the rays of the reflections.
Glossy Reflection
Fully glossy reflection, shows highlights from light sources, but does not show a cleat reflection from objects.