Read here:
Settings > General > Accessibility >
VoiceOver describes aloud what appears onscreen, so that you can use iPhone without seeing its screen.
VoiceOver tells you about each item you select. The VoiceOver cursor (a black outline) encloses the item and VoiceOver speaks its name or describes it.
Touch the screen or drag your finger over it to hear the items on the screen. When you select text, VoiceOver reads the text. If you turn on Speak Hints, VoiceOver may tell you the name of the item and provide instructions—for example, “double-tap to open.” To interact with items, such as buttons and links, use the gestures described in Learn VoiceOver gestures.
When you go to a new screen, VoiceOver plays a sound, then selects and speaks the first item on the screen (typically in the upper-left corner). It lets you know when the display changes to landscape or portrait orientation, when the screen becomes dimmed or locked, and is active on the Lock screen when you wake iPhone.
Note: VoiceOver is available in many languages. Go to Settings > General > Language & Region to choose a language.
Another way:
iPhone can read the contents of the screen to you, even if you don’t use VoiceOver.
Turn on Speak Screen. Go to Settings > General > Accessibility > Speech.
Have iPhone speak the screen. Swipe down from the top of the screen with two fingers. Use the controls that appear to pause speaking or adjust the rate.
Highlight what’s being spoken. Turn on Highlight Content (a command that appears when you turn on Speak Screen), and the current word is highlighted as it’s spoken.
Ask Siri. Say “speak screen.”
You can also have iPhone read just text you select—see Speak Selection.
