Facebook is a funny old thing. It's wonderful and dreadful at one and the same time. I allows you to stay in contact with old friends, but sometimes too much... When people get you down, and you have to do something, there are a variety of possible responses.
When people advertise witchdoctors on the Facebook group of your church (we get one or two a week) then you can report the advert to Facebook and block the person. This is pretty severe. It means people can't contact you at all and Facebook apologises for the inconvenience and annoyance the person has caused you.
When someone was accepted as your friend by accident, someone you don't know and who shouldn't be in your list of friends, you can "unfriend" them. It is advisable NOT to do this to people you know as they take it badly!
When someone uses Facebook in ways you find unhelpful (venting, for example, or foul language or whatever) you can "unfollow" them. This means you are still their "friend", they can still contact you, but you don't get shown every update they post on Facebook. This is a VERY USEFUL option.
When someone puts on a piece of information, like "We got engaged!!!", and you express your congratulations wholeheartedly but you don't need to be told every time the entire population of the continent of Europe expresses its congratulations - then you can "Turn Off Notifications".
There are lots of ways of whittling down the tidal wave of stuff that Facebook throws at you, filtering out unwanted debris and trying to keep things civil and capable with.
It just takes a bit of finesse.