https://www.cnet.com/news/with-airplay-2-apple-homepod-smart-speaker-gets-multiroom-audio-stereo-sound/

AirPlay 2 is the latest version of Apple's audio streaming service. AirPlay already allows music, podcasts and other audio to stream to the Apple HomePod smart speaker, Apple TV and additional Airplay-compatible devices. 

This next-gen iteration adds two features we've been anticipating since WWDC 2017: multiroom audio and stereo sound.