You can hold the Eye Sensor Button to quickly access the button’s function menu.
If the eye sensor button is OFF, you have to press the button to switch between the EVF and the rear screen.
If the eye sensor is ON, the camera will automatically switch between the viewfinder and the rear screen when you move close or pull away from the camera.
When this is on and you pull away from the camera the rear screen can show either the Super Control Panel or the actual live view. Pressing the eye sensor button toggles which view you get!