What is text me when you get home meaning?

The phrase "text me when you get home" usually means that the person who said it is concerned for the safety of the person they're talking to, especially if they are out late at night. By asking them to send a text message once they arrive home safely, the speaker can alleviate some of their worry and confirm that their loved one has made it back to their destination without incident. This phrase is also commonly used as a polite way to say goodbye after spending time together.