What does orthogonal three-axis pan-tilt mean?

It is a kind of photographic equipment, which is used to stabilize the camera or video camera and realize smooth movement. By using orthogonal three-axis pan/tilt, a photographer or cameraman can achieve smooth movements, such as horizontal translation, vertical rotation and pitch tilt, which is very useful for shooting stable videos or achieving accurate photographic effects, especially when moving photography or motion tracking is needed.