Culture and language are often tightly connected and one represents another. So, I quite agree with the viewpoint that to learn a language really well, someone has to learn about the country where this language is spoken and without knowing the cultural, , someone cannot truly master a language.
We learn our mother tongue from our surroundings, parents, teachers, and relatives and through life experience without reading books or attending classes. We know when to use an expression and when to use sarcasm, then when to and when to avoid a word. This all seems natural to us only because we have learned it from our experience, not from books. Similarly, when learning a foreign language, we must learn about the people and their lifestyles in order to properly learn this language. For instance, I had many Spanish-speaking friends in my school and I had three courses in this language. I am capable of communicating in Spanish and expressing my ideas but if someone asks me this language, I would say almost nothing. This is because I do not know the cultural and historical aspects of the Spanish people that well.
Moreover, people learn to communicate in a different language when they migrate to a different country without formal language learning training. I personally know many who can speak English fluently after they had migrated and stayed in an English Speaking country for a while. Since they had exposure to the culture, people’s lifestyles and environment of an English-speaking country, they learned the language very well.
Thus knowledge about a country, its citizens, history, lifestyle, cultural and traditional aspects to learn the language spoken there. We learn better by doing something than reading about it and this is also true while learning a language as well. A language is better learned when we know about the people and the country who own it.