Visual acuity is a measurement of a person's ability to see distant objects well. This is assessed by way of individually testing each eye's ability to read a series of numbers or letters on the "Snellen's chart".
A person with poor visual acuity could have underlying issues with short-sightedness (myopia), astigmatism, cataract, or other eye diseases, and follow up with an assessment by a qualified optician and/or ophthalmologist is recommended.