The real meaning of Non-Duality or Advaita refers to that which cannot be known. The very act of trying to define something that cannot be known is giving it shape and form to something which has no shape or form. Others who fully understand Advaita explain a very radical form of it by simply saying that the person or individual is an illusion.
When a person is on the quest for enlightenment and hears this message, its hard for the mind to even comprehend how the person is an illusion. Most assume it means the person is not real however, the word illusion can also be defined as something that is viewed incorrectly. Unfortunately no one can truly learn Non-Duality (Advaita) unless they have the recognition an "Awakening" Enlightenment, Nirvana, Oneness.