With macOS Catalina, Apple is introducing new assistive technologies to help every user get the most out of their Mac. Voice Control is a transformative technology that enables users who can’t operate traditional input devices to control their Mac entirely with their voice using on-device Siri speech recognition technology, which also ensures personal data is kept private.
https://www.apple.com/newsroom/2019/06/apple-previews-macos-catalina/

