what does it mean .message is not flagged .mark as UN read?

Question

this ,is an email question

Answer 1

These are just reminders you can give to yourself if you get a lot of emails. You can "flag" an email (a small flag will actually show up) as a reminder that you need to do something, or it's an important email. You can mark an email as "unread" to remind yourself not to delete it. These reminders are tools for you to use any way that's best for you.

Answer 2

flagged means it will show up in the front of the inbox