The Backups tab shows your restore points and creates new ones.
Press Create: name the backup (or accept the suggestion), choose the scope - the whole account or specific domains - and whether it is full or incremental. Incremental records only what changed since the last one, so it is faster and smaller; full stands alone.
Each restore point lists what it contains. From a point you can download the archive - keep a copy off the server before risky work - or restore, which the hint on the page describes: restoring puts things back AS THEY WERE, overwriting what is there now.
Backups marked encrypted are stored encrypted at rest.
Rule of thumb: create a point before every upgrade or migration, and download one copy of anything you could not bear to lose.