They probably mean a bar at the bottom that shows what's going on. All browsers used to have it. Then it dropped to just showing which URL was currently loading. I don't think they even show that now. Most of what it had is accessible in greater detail with developer tools, but it was nice to have a little summary down there.
It depended on the browser, but I remember IE6 showed how long a page took to load, zone/where it came from (local, internet, "Trusted Sites," etc). All I can find when Googling are old posts on how to fix it when some plugin broke it. I think Firefox's version used to be something you could add, remove, and edit with Firefox's toolbar customizer thing.
Thanks for taking time to research it. It also had page zoom and other useful options. It seems as if the need for more viewing surface killed the status bar.
