Have your Mac speak alert messages
You can have your Mac speak the text in dialogs and alert messages and notify you when an app needs you to perform an action.
On your Mac, choose Apple menu
Select the “Speak announcements” checkbox, click Options, then set any of the following options:
Voice: Sets whether alerts are spoken by the system voice or a different voice.
Phrase: Sets the phrase you hear before the text of the alert message. By default, the name of the app associated with the alert message precedes the message.
Delay: Sets the number of seconds you want your Mac to wait before it speaks the alert message.
Click OK.
To turn off this feature, choose Apple menu > System Preferences, click Accessibility, click Spoken Content, then deselect the “Speak announcements” checkbox.
You can also use VoiceOver, the spoken interface for macOS, to hear descriptions of every item on the screen and to control your Mac using the keyboard. See the VoiceOver User Guide.