The Windows 10 Creators Update for PCs will be available starting on April 11 but is already rolling out to the Xbox One. Nevertheless, the update is rolling out gradually, so it may not be available on your Xbox One yet.
With the Creators Update, Microsoft is introducing a couple of new features to the Xbox One. The console now has built-in game streaming, an improved dashboard design and new features for Cortana. Furthermore, the update will improve the Achievements leaderboard and the Guide.
A detailed list of all new features can be found here.