When you block someone on Facebook this person is removed from your friends and can no longer interact or communicate with you in any way, except within applications and games you both use. Since blocking is mutual, when you block someone, you and this person won't be able to:
- See each other's profiles
- Find each other through the Facebook search box
- See each other in the list of friends of your mutual friends
When you remove someone from your Block List, this person will be able to view your profile and contact you again within the restrictions of your privacy settings. If you were friends before the blocking, this connection will not be restored unless a new friend request is accepted. Also keep in mind that, during the next 48 hours after you unblock someone, you will not be able to block this person again.
How to Use Facebook >> Friends and Users >> What happens when you block someone on Facebook?