The "countdown" is in Italian but the other text is not, as you can see. Also, the text of the password prompt of the lock screen is in English too, "Enter password". I tried switching the language to English and back to Italian but it didn't work. I'm running OS X 10.11.6.
Solved by running
Solution from the ‘If there’s more than one user account on your Mac’ part from the Apple KB article Change the language used at the login screen on your Mac.