The hub I wrote is in red, which means "not published." What does that mean? Not published here in Hubpages? I was able to see it after I saved it. Can other "hubbers" see it and comment?

Red means it's not published yet, you must not have hit the publish button, however, it will show in your list of hubs on your My Account page.

No one else can see it, only you, so they cannot comment on it either. It will get crawled by the bots tho' but it does not get real page views until you hit Publish Now in the editing section of that red hub.

Hope this helps.