This is not a feature per se but a new Autofill API introduced by Google in Android O will allow password managers to work more elegantly in the OS. Using the API, password managers will be able to use the Autofill API to easily fill your login credentials in other apps and services.
As of now, LastPass is the only password manager in Android to offer autofill functionality. However, the feature can be wonky at times since it has been implemented by using the accessibility feature of the OS.
With the new Autofill API in Android O though, this should no longer be an issue. Once the respective developers update their app to take advantage of the new API, users will automatically be prompted by the password manager they use to autofill information in a login window of an app. For added security, users will first be prompted to verify their fingerprint.
AgileBits, the developer of 1Password, have already teased an updated version of their app that takes advantage of the new Autofill API in Android O. You can find a video of the updated app in action here.
Once Android O drops, expect all popular password managers for Android like LastPass, Enpass, KeePass to be updated to take advantage of the new Autofill API.