I wanted to know about the G'hi too since I forgot what it was. I did some research and this is what I founds since no one was helping you out. Hope this will help you understand.
G'hi is a player's life force, and goes up as they talk, heal other players, and interact with other player characters in general. G'hi makes the characters slightly faster, stronger, and more resilient, but increases in its effects as the player spends more time with others (grouping up and forming parties is encouraged right off the bat). G'hi gradually drops when you're not around other players, but your G'hi abilities will reassert themselves as soon as you start interacting with others again.