What is a camera gimbal?
A gimbal is a device that allows smooth camera motion when handholding a 
camera. 
The DJI Ronin RS 2 is for small still cameras. It has three motors that balance 
the movement of the camera. In ordinary use, the motors adjust to the 
movement of the hand grip. Use the gimbal for travelling shots that follow a 
subject or move around a subject.
You can also do special effects, like getting the gimbal to execute a series of 
preprogrammed movements, follow the movement of a phone, or move 
during timelapse photography.
The drawback, when using the gimbal, is the difficulty in operating exposure 
and focus settings while shooting. You will want set up exposure before 
recording and use autofocus.