If you're talking about these
those are icons you can use to mark a post. They're called 'Post Icons'
and are used to represent the intention of the post, if that makes sense.
For instance: if you post a question you might want to tick the question mark and it will show up next to the post, although adding those icons is not necessary. It's a personal preference as to whether or not you use them.
As for what they are supposed to represent, some are obvious like the question mark and the exclamation point. Others are a little more cryptic and are probably best ignored, but I'll try (most folks don't use them so I've not really given it much thought
The first one on the left (fire?
)I suppose could represent a hot topic. The next one (star
) I suppose could represent something, but I have no idea.
Bottom line: if it's not obvious then I guess the decision as to what they mean is up to individual interpretation.
Hope that helps explain things.