Dictation expands further in the November 2019 Xbox Update with support for more languages! With either a headset or Kinect, you can press the View button whenever the keyboard is on screen to start converting speech to text. To change your preferences from your regional default, head to Settings > System > Language & location to select your keyboard & dictation language.
Supported languages and regions include English (US & Canada), English (India), English (UK), Spanish (Mexico), Spanish (Spain), French (Canada), French, German, Italian, Norwegian, Portuguese, Japanese, and Simplified Chinese, with more to come in future updates.