I think you are draging the wrong thing to your toolbar. The 'Link Below' they mentioned is the words 'Snipe It Now' in large bold print, not the picture of the box at the very bottom.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .