@pedronapoleaojr
You need to add a translation file here for your language
(If It does not  already exist for your language).

For Example: We have added messages.en.yml for english here.

https://s3-ap-southeast-1.amazonaws.com/cdn.uvdesk.com/website/3/202002075e3cec5d9e4d3translationfile.png

Now make a entry for your locale in uvdesk.yaml file.

c845fda5-1c50-442f-96cd-53c7c7744179-image.png

And Finally check your choice language by passing it into url.

https://s3-ap-southeast-1.amazonaws.com/cdn.uvdesk.com/website/3/checkTranslation.png

Now you can make it your default language.

Locate file config->packages->translation.yaml  open translation.yaml  and make changes as given below.

default_locale:    your_locale(en, ar etc)
      fallbacks:   
                     -  your_locale(en, ar etc)
 
 
Clear your project cache by:
 
php bin/console c:c