Hello there again Helen, Perhaps you may like to rephrase your questions to the first person singular, (you instead of they) because I can only speak for myself and why I use the forum, see what I mean?
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 .