The anti-reflective treatment is nothing other than the suppression of those reflections on the surface of the lens, with the aim of eliminating or bringing to a minimum any reflection that is on the surface.
During the day your lenses receive a lot of light from different natural and artificial sources, without an anti-reflective treatment, the lenses behave like window glass in which you will see yourself reflected.
Normal lenses without anti-reflective have a transparency of 90% (the other 10% are reflections); Those who do have the treatment achieve close to 99.7% (only 0.3% are reflexes).