This is very simple sundial app, which draws "archaic" sundial (that is, sundial for local solar time, and 12 hours of day counting from sunrise to sunset). Such time was used e.g. in biblical time.
By default, sundial is presented as vertical one (as clock on wall), but you can change it to horizontal mode - to tick as our standard, mechanical clock.
You can set how hours are labelled: original roman counting system (default), modern roman counting system (with subtractions), and western digits.
You can count time from sunrise to sunset (default), but you can also take into account dusk and dawn, either civil (center of Sun is 6° below horizon), nautical (12°) or astronomical (18°).
Time is counted for your geographical position (if app is allowed to use geolocation), or for entered latitude/longitude pair. If app cannot access current location, it uses (by default) location of Kraków (Poland).