Thread:Support/About MediaWikii:Tpt-sections-prioritylangs/reply

"Prioritizing languages. You can also define a list of languages that you specifically want translations into. When translating into a language that is not listed in the priority languages list, translators are given a notice. You can also prevent the translation in other languages, say if translations are actually used elsewhere and you won't be able to use them but in some languages. The page will behave like a discouraged page (see previous paragraph) for the languages not in the priority list." From: https://www.mediawiki.org/wiki/Help:Extension:Translate/Page_translation_administration#Life_of_a_translatable_page

Primary language is the first language the user signs up to be a translator in the Special:TranslatorSignup special page provided by Translation Notifications extension.