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Go to the course in question
Go to Course Administration > Settings
Modify the course full name and course summary using mlang tags
This is described in full in the Translating Web Pages article, but the same principle can be applied to the course full name, course summary and most other fields that are visible to learners
Click on the "Save and display" button at the bottom of the page
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By following the steps above, you've instructed the learning environment to only show the first topic to users whose preferred language is English. You may now place all your English content in this first topic.
If you follow the same steps as above with the second topic but set the restriction Language to "Français", then you will be able to place your French content in the second topic.
Note that you can have as many topics as you want, each with their own restrictions. You can also place the restriction on each activity if you prefer (rather than on the entire topic). Restricting the entire topic however is generally simpler to manage and less error prone.