In plain words
12. “Adhyātmavidyā vidyānām”
That which gives light is Vidyā
When the suffix “ya” is added to the root vid, the word “vidyā” is formed. “Ya” means that which, “vid” means light. The meaning by derivation is that “that which gives light” is “Vidyā”. So the word “Vidyā” fits “Brahmavidyā” alone. The ancients spoke of Jñāna as light and of ignorance as darkness. Just as light and darkness cannot stand at the same time in the same place, so Vidyā and avidyā cannot both stand at the same time in the same place. So every man travelling the path of progress must study Brahmavidyā and become pure in spirit.