Luiz
Hello Luiz and welcome to the forum 🙂
To your question: It depends on the context. There are the translation files (available on Github), which provide the core translation for the r3 platform. You can follow this link, download an existing file, translate it to Brazilian Portuguese and either submit a pull request or send it to us to include in a future release. You can build r3 yourself to get the translation immediately, but it takes some effort to do. If you provide the file to us, we can include it in a patch.
Besides the platform translation, there are translations for r3 applications. These can be transalted by you in the admin panel under Translations
to a language of your choice.