The staging area is a replica of the production area, and also an independent WordPress site at the same time.
As it has same environment as the production area, you can confirm the operation before you publish it online.
If the operation is successful at the staging area, you can copy it to the production area by one click. And it also corresponds to the target database table.
You can Copy content between the staging and production by using original plug-in at the dashboard of the production site.
You can delete or create a staging site from the control panel as needed.

Using together with Backup/Restore feature, enables the cycle as below only by the operation of the control panel.
[Create a site]→[Publish the site to test]→[Restore]→[Modify]→[Publish the site to test] →[Restore]→[Modify]→[Publish the site officially]