language overrides

Language overrides function can be found in Extensions > Language Manager – Overrides section of Joomla admin panel:

To avoid editing the language files of website, Joomla admin panel has the function of Language Overrides which allows you to customize the default variables with your own.

Language overrides is an optional file that allows the site administrator to override any language string in core Joomla or in an extension. There are two override files, one for the front-end and one for the administrative back-end.

You can find more information on how to use Language overrides in this tutorial.