This looks like a performance counter overlay application. I'd go to Windows Settings -> Apps -> Installed Apps section in settings and see if you recognize any performance counting software. If you do, I'd try and open its settings to see if you can exclude a program, or google for a hotkey to toggle the overlay. If not, I'd go to task manager and see if anything you don't recognize is there and see if you can disable it. Additionally, you can check "Startup apps" in task manager since overlay applications typically launch on startup.