There are several available languages in AcyMailing and this listing displays the list of languages of your website (Front-End). For each language, you can edit the AcyMailing language file to customize the translation.
Most of languages files are included in the package so during the AcyMailing installation process, the language files are automatically installed so you don't have to do anything on your end.
If the language is not included in the package, you should click on the create button and the latest version of this language will be directly loaded from our website.
Then you simply have to save the language to have it on your website.
If AcyMailing is not translated in your own language, you can easily add a language file in AcyMailing. Don't forget to share your translation so we can add it to the next release.