Scenes are snapshots of time. Using a calendar year as an example, you could create Scenes of just January, the second quarter, or the entire year. This allows you to quickly jump to a particular timeframe you have saved.
To create a Scene, position the timeline showing the timeframe you want to save, tap on the Scene button in the bottom right, then tap on New Scene and give it a name.
That Scene will then appear in that same Scene button popup, and in the Scenes List in the sidebar.