Scene Collections save all Scenes and Sources that have been added to it. Similar to Profiles for output settings, you can store multiple different collections of saved Scenes and Sources. Then, you can swap between different collections for different situations.
For example:
Note: Scene Collections also contain Global Audio Sources from Settings -> Audio
The "Import" option for scene collections allows not just for OBS Studio collections to be imported, but also supports migrating existing OBS Classic, XSplit Broadcaster, or Streamlabs Desktop scenes. Additionally it automatically adjusts OBS Studio scene collections created on other operating systems to the one you're currently running.