What Is HU?
Singing HU or chanting your secret word enhances your life and gives you strength. HU is a holy name for God which will lift you into the higher worlds.
But the name itself has even more meaning behind it. I would like to recommend a spiritual exercise which will be very beneficial to you in finding it out for yourself.
As you chant each long, drawn-out HU outwardly, keep asking inwardly, "What is HU?" Repeat the question mentally as many times as is comfortable for you, maybe two or three. In other words, with each outward HU, you are asking within, "What is HU? What is HU? What is HU?"
—Sri Harold Klemp
The Spiritual Exercises of ECK