I am looking at the question which is "What are the spam and offensive flags, and how do they work?". And it says that when a post accrued 3 flags (spam or offensive), it will be banished from the front page. What does the front page mean?
The front page is quite literally (as of now) the page you see when you first load a site. Internally, we're expanding that definition, where we consider any page that people commonly visit in order to find new stuff to answer to be the 'front page'. You might to go /questions, you might to go a certain tag feed - whatever, it's the first thing you see when you open the site looking for stuff to do.
Things we're currently working on entail making sure that you don't see awful stuff in those places (wherever they might be), while still leaving you the ability to drill down into it if you really want to. This would affect not only stuff that has been heavily down-voted and / or flagged, but also stuff that the system identifies as being of questionable quality. Some of this is in place now.
In short, starting soon, the 'front page' is whatever page users show as being the most visible on the site, based on behavior we examine when watching how folks find new questions to answer.
The spirit of it, to keep in mind (as Rose Red continues to build upon itself) is we don't want to put crap in your face when you first hit the site, unless you really want to see crap in order to help deal with it.