Compass and level are used for filling some field directly from within the S.U. form. Anyway, they can be accessed independently by the "three dots" menu in the upper right corner of the screen, within the "field tools" sub-menu.
The compass presents an arrow pointing to the head of the device.
Turning the device around will change the direction displayed by cardinal points (above the arrow)
and degrees (below the arrow).
Orientation is relative to the magnetic north.
Please note that, as usual with magnetic sensors of the mobile devices, the compass periodically needs to be calibrated.
Search the internet for methods to calibrate it (e.g., the "8 figure").
Always check its correct calibration (e.g., pointing the compass to a known direction) before a recording session.
The level simply indicates the slope of the device in degrees.