Address Bar is the bar which you find in a browser where in you can enter the website url and press Enter to load that specific website. Now with the never versions of firefox, whenever you try to Enter something in the Address Bar, it starts loading some related websites which were previously opened or else which are in your Bookmarks Section, but there is a option to remove this stuff.
Navigate to Tools >> Options >> Privacy
From the Location Bar menu, beside When using the location bar, suggest, you will get few options :
1. History and Bookmarks – It will display history and bookmarks
2. History – Address bar will display matches from history only
3. Bookmarks – Address bar will display matches from Firefox bookmarks only
4. Nothing – Firefox address bar will display nothing whenever you type something
Select your preferred option and click OK to save the settings
You are done.