Using a base snapshot, you can back up a base and restore it to an earlier version. Airtable automatically takes occasional snapshots of your bases, and you can also manually take a snapshot. It may be a good idea to manually take a snapshot of your base immediately before restructuring or otherwise making a large amount of changes to your base.
Taking a snapshot won't do anything to your existing base.
Restoring a base from a snapshot will create a new base without affecting your existing base.