You have exceptionally good eyesight at a distance and are much better at both detecting things and seeing details at distances greater than 100 feet. It'll help you in detecting things at a distance, or discerning detail a great distances. It can also be useful when using ranged weapons at these distances. This effectively reduces the difficulty pentalty of shooting at long and very long distances by 1 per step of this trait. You add the value of the trait when shooting at these distances.