You can turn your device's camera on and off at any time during zoom calls (provided you have the necessary permissions).When your camera is off, only your name and profile picture, if available, are visible by other users.
Press the Start Video button on the control bar at the bottom of the screen to turn on your camera.
To turn off your camera,press the Stop Video button that is placed in the same place
You can also use the following keyboard shortcuts.
Alt+V: Start Video /Stop Video
Command(⌘)+Shift+V: Start Video /Stop Video
Not: In video calls, the host can turn off the camera of any participant at any time by right clicking to the participant and choosing the option Stop Participants Video. But the host can not turn on the a camera that is turned off.Host can only ask that participant to turn on their camera by clicking Ask to Start Video.