The translation feature is based on the Bergamot project to provide users with a privacy-aware translation engine where the translation is done locally using machine learning, it’s never sent to a third party, and it’s optimized for consumer hardware.
This is cool, but beyond anything I wish the linux version of firefox used my default filepicker. It keeps choosing to use the gtk file picker instead of thunar or whatever else I choose.
FYI, the translation feature is available in the current stable version (v117), but it's disabled by default. To enable it, go to about:config and set browser.translations.enable to true. I tried it earlier on a German website and it worked well.