Eye dominance means the tendency of preference in using one than the other. This often happens to people with amblyopia and strabismus. These are extreme cases when one eye is weaker. Most people have just slight preference.
What's more, the direction people see from also affect the eye dominance. When people look to right, they are more likely to use right eye.
Some people have no eye dominance. They use both eyes.
If you belong to the left eye dominant, that means that your visual input is from left eye to the right one. The number of people with left eye dominant is less than those with right eye dominant ones. It is all controlled by the hemisphere of brain. It is to some degree similar to the laterality of right or left handedness. Usually the side of the dominant eye and the dominant hand do not always match because both hemispheres control both eyes. However what side of your eye dominant does not affect your vision. That is to say, left eye dominant does not mean they have better vision in their left eyes. They just input the vision from the left eyes. The both eyes vision will not be affected. If your eyes vision is affected, you could do some measures to improve it through the diet and rest.