What is a digital camera white reflector and what is it used to do?

A white reflector bounces more light into the shadow areas. You can use it for regular or digital photography, or even videos and filming. It's white so that it doesn't bounce any colors with the light into the shadows.

Some of them look like umbrellas, and they're used with a studio light facing into it to bounce softened light, instead of using harsh direct light. A flat one is usually handheld to bounce natural daylight or sunlight into a scene.

white reflector is used best during like a bight setting such as taking a picture of snow, its a white balance. I only pay attention to it when I do take snow shots.