Just as the name implies, large pupils is just to describe people with bigger pupils than most of people. I think people with large pupils may have a pair of pretty eyes. Usually, pupils dilate open in darkness. This is to allow light in to see. From this point, it seems people with large pupils may have good vision especially in overcast or in dark.
The pupil is the opening in your eyes that make light in. The iris controls the size of the pupil opening thus some people have large pupils, and some has small ones. The large pupil means the pupil opening is large to let a beam of light into eyes. Normally, it would occur when in dim or dark environment and prevent too much light in when in bright light.
Pupil is the small round hole in the iris center of the people's eyes. It is regarded as the channel for the light to enter into the eyes. When you buy the glasses and hear other people say large pupils, it means that the amount of light into your eyes is larger than that through the common pupils.