Flies have eyes that are very different from ours. Their eyes are called "compound eyes" because each eye is actually hundreds of little eyes compounded together. Each little eye has its own lens, rods, and cones, and transmits a unique signal to the fly's brain.
Though you may have heard differently, even though flies have compound eyes, they still see one image, just like us. This is because each little eye in the compound eye is pointed in a slightly different direction, so the light it senses is separate from the other little eyes.
The way a fly sees is similar to how a picture is formed on a computer. If you think of a picture on a computer, it is composed of many pixels that are in different places. Like the pixels in a picture on a computer, the information from the different little eyes gets put together to form an image. In this case, the fly's brain puts all the information from the little eyes together to make one image of what the fly sees.

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