I learned a lot of languages in my teens and 20s. I say “learned,” but don’t expect fluency. You shouldn’t try to have a very complicated conversation with me in any of them today. But there have been points in my life when I had dear friends with whom I only spoke Japanese or Norwegian. I can buy a watch in French and have occasionally exchanged very basic information in Spanish. Once I made a phone call in Italian—and the taxi showed up the next morning. At the right time!
But I’m not one of those people who can show up in a country, hang around in bars and youth hostels, and somehow magically “pick up” the language. All of these were pounded into my brain through large amounts of time spent in classrooms, going through flashcards, writing out sentences, memorizing dialogues, and so on.
All of that classroom-based learning meant that I often knew a lot, without really understanding how people really use these languages in the real world, and particularly how they avoid offending each other.