Your Mac’s Speak Announcements feature belongs to Apple’s Accessibility settings, which include several features designed to help more people access and navigate their devices efficiently.
When enabled, your Mac will speak out the text in notification messages. It will also notify you when you need to perform certain actions in apps.
How to Enable Speak Announcements
Before you get started, make sure that this feature works on your Mac: it’s only available for Macs running macOS Sierra and later.
To make your Mac announce notifications and alerts: