Seems a (somewhat misformed) message of a program running.
- Does it happen also if you boot into Safe Mode (Google how to do that in Windows 10, if you don't know)?
- Any suspect entry in the list of items that run at startup (a tab page in Task Manager)? That disable that, reboot and see if it disappears.
- Finally, delete all running processes (Explorer excluded, services not necessary since those don't display anything on the screen) in Task Manager. The last one for this text disappears is the culprit.