a.k.a. Quick Access (as in the Support Article)
Edge Swipe is a feature of the launcher in Fairphone OS, which lets you access your favourite apps by swiping in from the edge of the screen, thus leaving more space on the home screen. Here is how it looks like:
To edit the favourite apps, swipe and don't release, until a pencil icon appears. Swipe to the pencil and release your finger above the pencil. You will then be able to move another app to the selection.