TalkBack

TalkBack is an Accessibility Service that helps blind and vision-impaired users interact with their devices more easily.

This application adds spoken, audible, and vibration feedback to your device.

It comes pre-installed on many devices so you won't be able to install this if that is the case.

It's only activated if you explicitly turn on Accessibility:

1. Go to Settings
2. Select Accessibility
3. Enable TalkBack checkboxes