When you create a theme/article in the Resource module, it is set by default to be in the language of your Career Centre, the one displayed at the top right (FR here). Once the article is activated, it will be visible by all students who accepted to see French content in their profile (either as a main language or as a secondary language).
As a reminder, the main language is the website display language and the default language for content to be shown whereas the secondary language adds the possibility for users to view content in additional languages. Adding a secondary language means you see content in the Jobs, Events, Companies, Resources modules in various languages. This means that students who have a language selected as either their main display language or as a secondary language will be able to see this content.
To translate the content of the theme and/or article to another language, you need to select the desired language at the top right. The articles/themes created in other languages (French in that case) will be displayed but not activated. You can translate and activate them. The articles/themes will be visible in each language with their respective translations.
In the example below, the theme "Votre accompagnement" has been translated in English by "contacts & services". It means that the students with French as main language sees the French theme, the ones with English as main language see the English one.