The second tab is the “Sun Angle” display which shows you the precise position of the sun in the sky for any time of the day (or indeed night …)
The Elevation is the height of the sun above (or below) the horizon and the Azimuth is the angle of the sun with respect to due North.
Use the slider to change the time to observe how the sun moves in the sky.
Note that this is the tab to use when you want to change the time of day – any setting you make on this screen will be visible on the Sun Clock Tab as well.