Leukocoria is a big word that doctors use to describe something they see when they look into our eyes. It means that they see a white or bright reflection instead of the normal black part of our eyes. If you shine a flashlight into a person's healthy eye, you won't see much reflection. But if you see a lot of reflection, it could mean something is wrong with the eye.
Sometimes this can happen because of a cataract, which is like a cloudy part in the eye that makes it hard to see. But other times it can be a sign of bigger problems that need to be checked out by a doctor, like cancer in the eye. It's important to tell your parents or doctor if you notice this kind of bright reflection in your or someone else's eyes so they can help you figure out what's causing it and help you get better.