If something is blinding, it's so bright that it makes you lose your vision temporarily. The blinding light of a camera flash can be very annoying.
The bright or dazzling light of fireworks, a flashlight, or even light glinting off of a mirror or a diamond necklace can all be blinding, rendering you briefly unable to see. Anything you can't see through can be described this way, like blinding rain or the blinding white of a blizzard, and even pain is sometimes blinding. The word shares an Old English root with blind, blendan, "to deprive of sight."