See my screenshots, see the difference? Look at the orange button in the top left, if the left one is orange, then you just tap on the different fixtures to select it for the area limiter.
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 .