Visual acuity is defined as how sharp your vision is or how well you see, especially how well you see fine details.
A person who has perfect vision and who can make out fine details is an example of someone with high visual acuity.
the ability of the eye to discriminate detail, usually tested by comparison with the power of the normal eye to distinguish certain letters on a standard chart at a given distance, generally 20 feet
Sharpness of vision, especially as tested with a Snellen chart. Normal visual acuity based on the Snellen chart is 20/20.