Mailman is available with many different languages. (For a complete listing see http://mailman.sourceforge.net/i18n.html.) This means that, if your list has other languages enabled, you may be able to have the web interface, etc. in a language of your choice.
Note: This does NOT necessarily mean that all the posts sent to the list will be in the language you selected. Only the pre-prepared texts presented by Mailman will be affected by this setting. Posts are in whatever language the poster uses.
Your preferred language is set when you subscribe (see Section5.1), and can be changed later if the list supports more than one language.
To change your preferred language in Mailman,
If your list does not support the language you would prefer to use, you may contact the list administrator (LISTNAME-owner@DOMAIN) to see if it can be added, but remember that this may mean some work that the list and/or site administrator(s) do not have time or the ability to do.
If your language of choice is not available because no translation exists for Mailman, please consider volunteering your time as a translator. For more information you may want to consult the mailman-i18n mailing list at http://mail.python.org/mailman/listinfo/mailman-i18n. (i18n is a common short-hand for "internationalization" because the word starts with an i, ends with an n, and has 18 letters in between. If you mumble a bit, i18n even sounds a bit like "internationalization.")