Near sighted is quite easy. Your eye is too big so that the picture point (don't know the correct english translation) is infront of your retina. Eyes have two limits, near sight point and far away point. Both beeing the outer edges of the length spectrum you can clearly see. In a normal eye with -0 dioptrien the far away point is unlimited meters away (1/0). If your prescription is -1 dioptrien that means it is 1/1 meters away, -2 is 1/2 meters etc.
VR may work a bit different because you have other effects in play, meaning you can see things more sharply that are virtually further away, but i do not have experience with that.
Mind you optics was a long time ago so maybe someone corrects me. But i think the answer should be correct.