How to create it?
You can easily create a WordPress staging website by opening Hosting → Manage:

And selecting Staging under the WordPress section:

In case you don’t see the WordPress section, make sure to detect your existing WordPress website.
Once there, simply click on Create staging:

Then, specify the subdomain name and click on Create:

That’s it! Now you will have a staging website where you will be able to do all sorts of edits or configurations without breaking your live site 😊
NOTES:
Keep in mind that the staging feature is available on Business (Business WordPress) plans or above, as lower plans resources might not be enough for intensive websites
Staging websites are created as subdomains. In case you cannot create any more staging websites - you will need to upgrade your plan
For all staging websites, you will have exactly the same WordPress Dashboard as for the original website
Pushing changes done on the staging website is not possible yet, thus you would need to move files to the live website manually as guided here: How to move website's content to another domain name?