Exposure has two modes, each with its own column of buttons at the left edge of the screen. Automatic exposure is on by default. If the camera does not support manual exposure, only automatic exposure is available.
In manual mode you set ISO and shutter speed yourself; see manual exposure. In automatic mode the camera chooses them and you adjust the result with exposure compensation; see automatic exposure.
Zebra and False Color are available in both modes and help you judge exposure across the whole frame.