You can have screen information and moving green bars displayed on the render displays to provide information on license and performance among other things:
In the main menu click Extras an select Display screen info following which the information is displayed on the render displays. The same way the screen information can be disabled again.
As an alternative, you can also enable and disable the screen info by hitting Ctrl + Shift + D.
When the text appears in red there is no license for the render displays available and the information cannot be disabled. See also Licenses and functions.