Always named alphabetically, we know the next Android OS update will be codenamed Android N. Google will announce the Android OS version as usual at the Google I/O conference in May. In fact, first screenshots and features of Android N have already been spotted in the wild, mentioned in the Android Support Library 23.2.
The Bluetooth settings screen reveals the two features of Android N. It will have a DayNight mode (white and dark theme option), which will change automatically depending on the time. White and dark mode was a proposed feature for Android M (Android 6.0 Marshmallow), but canceled in the final build due to various reasons. Most likely, Google may fix all the issues and the feature will include in the Android N.
Another new feature of Android N will be the hamburger button and navigation drawer in Settings app, which enables users to access various settings instantly from any screen. That is all we can say now, but in all probability, the screenshot will be of Android N.
Google may announce Android N (probably Android 7.0) on May 18 – 20, 2016, but it should be already deep into the making. The screenshots reveals that.
Note that there is no guarantee that the above-mentioned features will include in the final build of Android N. You have to wait until the final build to get know about all the features of the Google’s mobile operating system, which will release (most likely!), at the end of this year (Source).