The grammar translation method of second language acquisition is virtually the only method used in most language courses taught in classrooms all over the world. It is also known as The Classical Method. This method was developed over centuries to teach classical languages. Latin and Greek were seen as important "dead languages" to learn in order to read ancient texts, understand the origins and basics of the grammar and vocabulary of modern languages as well as the influences Latin and Greek had on them.
Literally, you learn through the memorization of grammar rules and lifeless vocabulary (not taught in the context of real life speech) how to translate and read a piece of written text. Latin and Greek are still taught this way today, the same way as they have been taught for centuries. So are most modern languages. You engage in an unimaginably boring process and somehow, though no one tells you how, you are supposed to arrive at the goal you are seeking in taking these courses: spoken fluency.
The reason The Grammar Translation by design does not work to give you any degree of spoken fluency is because it concentrates on short and long-term memory. You have to engage in intense memory work to try and recall the rules of translation. You also have to try and engage memory for the massive amount of vocabulary you must remember for the written tests within the course and to perform translation tricks.
This method is still taught today because "that's how we've done it all these years." More than 40 years of linguistic research in second language acquisition is totally ignored in favor of, "that is how we've always done it." Tradition and blind allegiance is a woeful combination.
If what you are seeking is real fluency in speech and listening comprehension, then this method doesn't work. There really is a natural progression to acquiring speech no matter if it's your first or second language. It involves developing a "speech center" in your brain that is not connected to memory. When you are shown a picture of a cat, immediately in your brain you can utter the word "c-a-t" in your native language. You did not engage in short or long-term memory work in order to do this. It comes automatically without translation or even thinking. You "just know" the word for cat in your native tongue when you are shown the picture.
That's what you are shooting for in true second language acquisition. Not memory recall as is involved in The Grammar Translation Method. What you want is thinking in the language. The Grammar Translation Method is not going to give you that.