In writing, or especially in typing, when you read over something you've already written and make modifications as you go. For example, you read "happy, joyful, optimistic" and change it to "happy, joyful, and optimistic." Read/editing is usually done in a casual situation, like a Facebook
message to a friend, but can also apply to more serious situations, like your college application.
Martha was nervous about the message her text would send, so she spent a minute read/editing it.