A version is a saved copy of your page at one moment in time.
Every time you save an edit, the previous state is worth keeping. Versions let you compare what changed and go back if an edit was a mistake.
Builders vary widely here. Some keep a full history. Some keep the last few. Some keep nothing, so a bad save is permanent.
Think Bright Sites keeps versions of your pages as you and your project lead edit them. Ask your lead to show you an earlier version any time.
A rollback puts an earlier version of your page back in place of the current one.
WYSIWYG means what you see is what you get: you edit the page as it looks, not as code.
A staging link is a private address where you review your new site before it goes live.
Export is getting your site out of a tool in a form that works somewhere else.
Paste your URL. We rebuild it, show you the match, and measure the speed. No template. No blank page. Human review from start to finish.