If your post gets flagged, it means that somebody else believes it requires attention from mods. This could be for many reasons: it could need a better title, re-tagging, etc. Posts are also flagged when people think they break the rules and should be closed or hidden.
Posts with flags get added to a list of flagged posts in a page that only staff can see. From there, we can decide what to do with them, or keep the flags on posts to remind ourselves of them later.
Flags do absolutely nothing else. You should not worry about flags. Some people get very very stressed about receiving flags. Don't be like those people.
