I assume you mean the icons at the bottom right of each post?
From left to right:
- "Thumbs-up" (show you like or approve of a post, etc.)
- "Acorn" (give acorns to the post author)
- "Bookmark" (add this post to your bookmarked posts, accessible from the person icon at the very top right of the screen > Your Profile > Bookmarked pages)
- Post options (i.e. quote, edit, etc. - these vary depending on whether you are the author or not)
- "Report" (the exclamation mark - report a post - use this for spam or inappropriate posts)