For the longest time, voice commands such as "turn on Wi-Fi" on Android would give you a settings page where you could manually toggle your settings. In Android Lollipop, however, they work immediately.
As Android Police points out, voice commands for common hardware toggles allow you to turn certain tools on and off immediately. The search app will also provide you with a card to manually re-toggle the feature, which is handy for such features as the flashlight that you may need to toggle multiple times in a short period. The feature only seems to work on Android 5.0 or higher at the moment.