What does it mean to have Do Not Disturb mode in text messages on iPhone?

There are three main functions.

First, you can set the phone to turn on or off Do Not Disturb mode at a fixed time. For those who like to leave their phones on and put their phones next to their pillows when sleeping at night, you can set a fixed time to turn on Do Not Disturb mode at night and then turn it off the next morning.

Second, Apple allows you to set exceptions so that calls in your contacts can take precedence over Do Not Disturb mode. Including allowing all calls to come in, allowing calls from a certain group of people in the address book, or allowing calls from personal favorites.

The third type is repeated calls. When the same person calls within three minutes, the second call will no longer be muted.