This tutorial explains how to enable Cover to Mute feature on your Apple Watch. This small haptic technology allows you to rapidly mute the dinging sounds emitted by the Apple Watch when you receive a new message or notification.
The first step is to make sure that the Cover to Mute feature is enabled on the Apple Watch App installed on your iPhone:
Open the Apple Watch app > My Watch > Sounds & Haptics. Toggle the Cover to Mute switch On.
That's it; the next time you receive an alert simply place the palm of your hand (for 3 seconds) over the Apple Watch's display to toggle the Silent Mode.