Talkback is the default screen reader available for Android operating system. You can switch it on from
Apps > Settings > Accessibility > Talkback.
Just wait before you turn it on. Read this chapter completely before you turn on the feature.
The default interaction that is tap to select or open a screen will no more work when talkback is switched on. Read the concept explore by touch. In principle, explore by touch allows you to tap or touch anywhere on the screen and talkback reads out what is available under the touch area. Double tap activates the element.
The other navigation mode is the gesture navigation. The list of navigation gestures are available in the Talkback gestures page.