It wasn't to clear to begin with. (See note at botton of that page) But I am posting it again without reducing the image for this page. Check it now Michael.
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 .