Use the rotor to choose what happens when you swipe up or down with VoiceOver turned on.
Operate the rotor: Rotate two fingers on the iPhone screen around a point between them.
Change the options included in the rotor: Go to Settings > General > Accessibility > VoiceOver > Rotor and select the options you want to be available using the rotor.
The effect of the rotor setting depends on what you’re doing. For example, if you’re reading an email, you can use the rotor to switch between hearing text spoken word-by-word or character-by-character when you swipe up or down. If you’re browsing a webpage, you can set the rotor to speak all the text (either word-by-word or character-by-character), or to jump from one item to another of a certain type, such as headers or links.
When you use an Apple Wireless Keyboard to control VoiceOver, a speech rotor lets you adjust settings such as volume, speech rate, use of pitch or phonetics, typing echo, and reading of punctuation. See Controlling VoiceOver using an Apple Wireless Keyboard.