Levitation is one of the movement options that can be purchased in the Apellbine Tavern in Pandaemonium from <Seriphim> or in the Outer Dock in Sanctum from <Andreas>. The manual costs about 16 million Kinah.
When at rest, your character seems to be floating with small rays of light underneath their feet. When walking or running, they move as if on a snowboard, swaying side to side. When crouching, you are slightly off the ground on the "light rays".