The so-called blind spot is the point in the eye where the retina is interrupted and merges with the optic nerve. Since there are no light receptors in this spot, we cannot see in this point of the eye.
However, the brain compensates for this by the visual impression of both eyes - so that we usually do not see the blind spot. However, you can find the blind spot with a simple experiment: Draw two dots on a sheet of paper - 12cm apart and max. 1cm in size.
Hold the paper an arm's length away from you and close your left eye. Concentrate on the left point with your right eye; you can still see the right point by itself in the corner of your eye. If you now move closer and closer to the paper, the right point in the corner of your eye will eventually become a blind spot.