What does max. magnification mean in lenses?

The canvas those numbers are referring to of course is not your display, but rather your camera's sensor The maximum magnification describes how large can an image on your sensor be relative to the object you are photographing. If maximum magnification of your lens is 1:1 (or 1x), this means that if your object is 1cm long, it can 'burn' a 1cm long image on your sensor