Android's App Pinning feature allows users to temporarily lock their device to a single application, preventing access to other apps and personal data. To enable App Pinning, users need to go to Settings, navigate to Security or Security & privacy, find App pinning, and toggle it on. To pin an app, open the desired app, access the Recent apps/Overview screen, tap the app icon, and select Pin. To unpin the app, swipe up and hold or press and hold the Back and Overview buttons, entering a PIN if required. App Pinning helps protect personal data when lending the phone.