The watch has a microphone, but it does not have a speaker. You need to connect the device to a Bluetooth headset to play music.
Additionally, notifications are silenced and will only be communicated through vibrations.
You can set the vibrations to your desired level. You can also change the vibration pattern to Normal, Long, or Double.
You can do this by going to Settings, selecting Apps and Notifications, and clicking on Vibration Pattern. You can test out all three options and set the one you prefer.