What is what does the bell with a line through it mean on text messages iphone?

The bell with a line through it on iPhone text messages indicates that you have enabled Do Not Disturb for that specific conversation. This means you will not receive any sound or vibration notifications for new messages from that particular contact or group chat, even if your overall phone settings allow notifications. You will still receive the messages; they will simply be silenced. The message thread will remain visible in your Messages app, but you will only know a new message has arrived when you open the app and see the unread message indicator. This feature allows you to selectively mute conversations without muting all notifications on your phone.