You can translate the site from the admin area -> translations page. In order to translate a particular line, simply click on it in the translation column.
If you can't find a specific line, or word you can create it by clicking add new translation button.
You can click on Download button to download a translation file in .json format. You can then translate this file via some external translation service (Google translate, ChatGPT, paid translation providers etc.) and upload the translated file back via Upload button.
While you can translate the original (english) locale, it is recommended to create a new one (via +new localization button). This way you don't need to worry about overwriting it with future updates.