Watch OS is an operating system for smartwatches from Apple. All the smartwatches launched by Apple come with the Watch OS from Apple.
Apple has pushed an update to the watch OS today. The new Watch OS update comes as Apple Watch OS 3.1.3 beta 2. The 2nd beta of watch OS 3.1.3 has been pushed to developers. So please don’t get confused with public beta. The Update can be downloaded from the Apple Watch app in your iPhone. The iPhone you’re using must have iOS 10 or higher.
The company hasn’t announced any specific changes or features coming with this update. But it is Sure that the latest update i.e. 3.1.3 beta 2 brings some under the hood changes to the system. It bring system improvements and bug fixes.