When you follow people, you'll see their public activity in the activity view of your news feed. If someone you follow stars a public repository, GitHub may recommend the repository to you in the discovery view of your news feed. To follow someone, visit their profile page and click Follow under their profile image.
Um jemandem nicht mehr zu folgen, rufe seine Profilseite auf und klicke unter dem Profilbild auf Unfollow (Nicht mehr folgen).