You always have to use many different packages within your application. Sometimes, these packages comes with their own language files. In case you want those specific things in your own language, then you can override them.
Instead of changing package's core files you can change them you may override them by placing files in resources
For example, if you have to override the English translation strings in
validation.php for a package named
laravel/nova, you should place a language file at: resources
/lang/vendor/nova/en/validation.php. Within this file, you should only define the translation strings you wish to override. Any translation strings you don't override will still be loaded from the package's original language files.