Question

our eye is a lense but how are others able to see their reflection in our eye​

Answer 1

The images we see are made up of light reflected from the objects we look at. This light enters the eye through the cornea, which acts like a window at the front of the eye.  Because the front part of the eye is curved, it bends the light, creating an upside down image on the retina.

Answer 2

Distracting glare comes from light reflected off the front of lenses so that others can't see your eyes, and from light reflected off the backs of or within the lenses so that you see reflections in your lenses. ... The unprotected eye will respond to discomforting glare by squinting and constriction of the pupil.