Complex sentence: The user does not see the stylus, handle or his/her hands as they are hidden behind the mirror, instead he/she see a virtual handle and stylus which are calibrated to appear in exactly the same position as the real handle and stylus.
Split into simpler sentences: The user does not see the stylus, handle or his/her hands directly, as they are hidden behind the surface of the mirror. Instead he/she sees a virtual handle and stylus calibrated to appear in exactly the same position as the real handle and stylus.