One of the first things new French learners notice early on is just how hard the language is to understand. It’s not obvious to most French learners why this is; only that French seems to become significantly harder when it moves from words on a page to words coming out of a person’s mouth.
Who the fuck master French language ? I don’t think I’ll ever master it, even though I’m born there, and still living there, using it every day
If you use it every day without struggling - or better, without thinking about it - you have mastered the French language. Whether you know the intricacies of the grammar and regardless of the extent of your vocabulary, mastery of a language is first and foremost defined as how comfortable you are using it without thinking about it.