If you have a person on Facebook and now changed your mind, you need not to worry because the process of unblocking a person is very simple. If you want to know How to unblock someone on Facebook Android, follow below mentioned steps:
Open the Facebook App
Click “settings”, in the “settings & privacy” column
Now click “Unblock” placed beside the name of the person.
Here you go. You have learnt the process to unblock a person on Facebook.