In the past few versions of Android, you could access your Google account-related settings via an app icon in your app drawer, like the one used in the featured image in this article. From there, you could opt out of ad tracking, look at apps connected to your account, and a variety of other things. In Android M, these have migrated to the system settings menu.
The “old” method was never very intuitive, so this change makes sense.
[Android M Feature Spotlight] Google Is Now A Top Level Item In System Settings Menu, Previously Only Accessible Via App Icon Shortcut was written by the awesome team at Android Police.