It can be daunting, right? The last time you learned a language, it took you nearly twenty years to be fully competent and you’re still learning things about your native tongue, facets and subtleties that might be forbidden to others. And so when you encounter someone bilingual, trilingual, or–good help you–a polyglot, it’s like being in a room with a living deity capable of feats to him simple and to you utterly unassailable. Luckily, I’m here to relate that this really isn’t the case.
When I was in grade school, I took French for many years, time in which I happened to build some approximation of a standard French pronunciation, but when I see full adults trying to learn a language, speaking it without an obviously foreign accent is often a skill utterly beyond them. The further back you go, the more that can be intuitively adopted, the easier it is to get native fluency, but you have to remember that you spent twenty years getting your native fluency in your own tongue. If someone insists to you that he has native proficiency in several languages, he either grew up speaking all of them in his household, he’s a genuine polyglot, or he’s a simple liar that doesn’t know what he’s talking about.
Generally, if someone says that he knows French in addition to his mother tongue, he means that he can read French and speak it for the most part without the aid of a lexicon, but he’s never going to insist he can equal your typical native speaker in knowledge of all those myriad subtleties.
Now, I’ve got experience in French, German, Sanskrit, Classical Greek, and Latin. The first of these I simply don’t have the time to pursue anymore, though I can usually get through a reading of French; the remaining two languages I can read more than adequately, but nevertheless I’m far from being a master, but most professors would nevertheless term me fluent. And that’s just the thing; “fluent” in this context is still a matter of extent but for the most part it means “good enough.”
I’m always learning more about Greek and Latin, and I’m slowly but surely becoming a more excellent reader. That’s how it is for most people. It’s a continual process that never ends. There is no peak mastery; there is always at least one more hill. That’s just the way it is.