Once the proper configuration profile has been installed from the Apple Developer Center, the new watchOS beta can be downloaded through the dedicated Apple Watch app on the iPhone by going to General --> Software update.
To install the update, the Apple Watch needs to have at least 50 percent battery, it must be placed on the charger, and it has to be in range of the iPhone.
It's not yet clear what features will be introduced in the watchOS 4.3.2 update, but as another 4.3.x update, it's likely to be minor in scale, addressing bug fixes and making other small improvements to the operating system.
watchOS 4.3.2 is likely to be one of the final updates to the watchOS 4 operating system. Apple has begun work on watchOS 5, which will be provided to developers next week at the 2018 Worldwide Developers Conference.