This is usually used for long, heavy telephoto lenses. The lens is placed onto the mount. Then the camera is attached to the back of the lens. Then the position of the camera and lens assembly is adjusted forward or rearward until the lens is balanced from front to rear. The center of mass of the camera and lens is now centered as close as possible to the pivot.
Then, when the lens is pivoted upward or downward, the entire camera and lens assembly stays centered over the vertical axis of the tripod. It has no propensity to fall over forward or rearward and the lens tends to stay pointed at the same vertically referenced angle.
This isn’t intended as a camera mount for general photography. It is a special mount for long, heavy lenses. My Manfrotto gimbal mount is rated by the maker for up to 44 pounds (about 20 Kg).