Definition - What does Truth mean?
Truth is what is factual or honest, something that is reality or can be proven. The idea of Truth, as practiced in yoga, is about understanding the difference between making a judgment through one’s own perception and actual observation of reality or the facts of a situation through growing self-awareness.
Yogapedia explains Truth
Within yoga and the "Yoga Sutras," Truth is one of the five restraints, or yamas, that individuals practice by restraining judgments or opinions regarding reality through one’s own perception.
One of the aims of yoga, through practice and meditation, is to become more aware of the true Self and, thus, the Truth.