What does a red bubble on the message app means

Hello IknowUknow,

That's a great question, and you've come to a great place for help! The red bubble that appears for the Messages app, can also appear for other applications as well. This is a notification bubble which can appear when you have an unread message.

You can also find some great information about other notification alerts in the following article.

Use notifications on your iPhone, iPad, and iPod touch

Have a great day!