A change to the Facebook's News Feed algorithm means you'll be seeing fewer of your friend's Spotify songs, Instagram Likes and other third-party app activity. If you have auto-sharing turned on — like sending all Instagram pictures to Facebook by default — those posts will be less likely to appear on your friend's feeds. But if you actually share to Facebook through an app, manually — adding a comment, then pressing the "Share" button — your friends are more likely to see it. Basically, Facebook will filter out what is automatic, in favor of posts that you made an effort for your friends to see.
Facebook has found that friends are less likely to interact with auto-shared stories than with manually shared posts. The change does cause issues for apps that rely on massive sharing, like news readers. Even though some third party apps are upset with the change, it is better for user experience. It means people actually see what their friends care about, not every single thing their friends are doing on the Internet and set up sharing for (possibly by accident) when they downloaded it.
Cleaning up the algorithm also means it'll be easier to see what many of your friends have in common. Instead of seeing ten posts from ten friends all sharing the same song, you will see that song once, and below, "10 of your friends shared this."
It also means there will be less clickbait on your News Feed. I, for one, am glad I won't be seeing the same cat meme fifty times a day.