What does it mean? First, it does not mean ‘unfriend’. There are two choices you have when you unsubscribe from someone in your News Feed (or you can go to their page and unsubscribe). In the News Feed you have:
The first one unsubscribes you from getting that person’s “stories” in your News Feed. The second one unsubscribes you from getting that person’s “updates” in your News Feed. So what in the heck is the difference?
The first option you get after you’ve commented on post they’ve made. Now their post is getting lots of comments and since you commented, you now become part of their “story” and thus, you are getting an update every time someone comments. “Stories” are how Facebook comprises your News Feed (since their last update), and these are posts that either a) have a photo or video, or b) have comments from people. The bland status updates from friends who just write text, unless someone comments on them, get pushed way down to the bottom and you probably will never scroll that far to see them. However, they will appear in the News Ticker in the upper right.
The second option allows you stop getting any kind of status update that they post from now on, which is indicated in the self-select option you get when you subscribed to their feed. Oh wait, you didn’t actually subscribe to their feed, Facebook automatically subscribed you to all of your friends when they rolled out this new feature. So, you will need to go to that person’s page and click on Subscribe in the upper right and select which types of updates you want to get from that person, if any at all. If you don’t want to go through the trouble of “unfriending” and dealing with the repercussions, then unsubscribing from their status updates is a nice alternative.
The good news? Neither of these options alerts the other person. Nor does “unfriending” them. They never know you are not seeing their updates. And they only know you “unfriended” them if they go looking for you. Meaning, if they go to type your name in to tag you in a photo or post, you won’t come up automatically; and when they go to your page they will see “Send Friend Request” which will be a dead give away.
See this post for how to unfriend on Facebook since the new changes rolled out in October.