Optometrist, President, Ontario College of Optometrists and Vision Therapy Expert, Dr. Patrick Quaid provided a full chapter to some of this in my book, Cyber Sober: A Caregiver's Guide to Video Gaming Addiction.
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 .