EMUI, or Emotion UI, is Huawei's own customized fork of Android. Version 5.0 is based on Android 7.0 Nougat, so by updating your P9 Plus to EMU1 5, you'll get all of Google's major enhancements alongside Huawei's refreshed, refined launcher.
Apparently, the update carries the build number VIE-L09C432B360, and is making its way to the single-SIM P9 Plus across several nations in Europe including Germany and Romania. Many of those in receipt of the update are not enrolled in the beta program, so it looks very much like the end user roll-out is now upon us. If you own the P10 Plus, this is promising news, though please be aware that if your model is carrier-branded, it could be a little while longer before this update reaches you.
Moreover, there's been no official word from Huawei on this update as yet, so P10 Plus owners shouldn't go dancing a victory jig just yet. Still, we'll pass on any specific details as they're made available, so stay tuned.