According to the Merriam-Webster Dictionary, the definition of truth is "sincerity in action." Therefore, when you know who you are, all your actions are rooted in sincerity.
From a spiritual perspective, truth is the ability to know who you are. (In Oneness, there is no such thing as who you are not.) Truth is allowing the essence of who you are to open your heart to you. Truth is “expansiveness”, it is “opening,” it is energy. And yet, it is nothing; it is no thing. And, of course, truth is in everything.
Trying to find the “right” way, or even the “highest” way, to explain or understand truth is like trying to find the “right” or “highest” expression of God. There is no “highest” expression. God simply IS. Truth simply IS.