Tap the location marker in Apple Maps on iOS and it will pinpoint you. Tap it again and you’ll enter a compass mode that rotates the map based on the direction you (or, to be more precise, your device) are facing. It’s a handy way to get a good, relative view of where you are.
Tapping the location marker a third time disables compass view, but leaves the map in its last orientation. If you need a quick way to point north again, tap the compass icon in the upper right.

Apple Maps compass