Before we get to the answer for this, we should talk about looking at the Sun. It's not a very good thing to do. It's fine if you accidentally catch it in the corner of your eye every once in a while, but looking at it directly even for a few seconds can cause permanent eye damage. So try to keep your eyes away from the Sun and bright lights as best as you can.
Sometimes a bright light, like a camera flash will sneak up on us and we can't avoid them. The lights cause us to see ghost-like spots and blobs that seem to float across our fields of vision. The parts of our eyes that are sensitive to light are called retinas. Really bright lights cause them to have a very strong response that they aren't used to. They're still reacting and our brain is still seeing images, even after the bright light has disappeared.
This reaction and these ghost spots disrupt our normal vision because our retinas are now desensitized or unable to react as well to the other light around us.
When our brains trick us into seeing something after an image or light changes, it's called an afterimage. It's a type of optical illusion. Have a grown-up help you find some examples of afterimage illusions. One well-known example is an American flag that looks black, magenta and cyan. After staring at it for 30 seconds and then looking at a white wall, your brain tricks you into seeing an American flag in its regular colors: red, white, and blue.After looking at these illusions, do you think you can always trust your eyes?