Internationalization, Localization and Translations
Internationalization is abbreviated as i18n (because there are 18 letters between the i and the n).
i18n refers to making b2evolution translatable into other languages. It has to do with marking up strings in the PHP code so they go into the list of translatable strings. It also has to do with providing comments to translators, so they know what they are translating.
Localization is abbreviated as l10n.
l10n refers to making b2evolution work in a specific language or Locale. It has to do with translation of course. I also has to do with setting date and time formats for example…