One should not conflate the term fluency with mastery, which is something quite different altogether. Whereas English language fluency is a skill attainable to most if not all committed English language students, mastery requires a number of years of extensive language study and a phenomenally broad knowledge of vocabulary and the many exceptions to grammatical rules. There are indeed few English language learners whose skills have yet reached this level. Mastery, one could therefore argue, is the pinnacle of the English language mountain, and one cannot climb to its great height without gaining fluency on the way.
Fluency, then, can be considered as something as a stepping stone in the intrepid learners’ expedition to the summit of English language learning. There are three core elements to fluency which students should spend significant time studying in order to consider themselves fluent. The first and most obvious is of course written proficiency, the ability to communicate effectively in formal or informal correspondence with English native speakers. Gaining a formal qualification in English studies is by far the most effective way of gaining a fluent proficiency in written English.
The other two core elements, spoken English and experience of English cultures, tend to go hand in hand. There is truly no substitute for seizing the opportunity to explore the real English speaking world which exists outside of instructional videos and text books. Any form of study or employment in an English speaking country will very quickly yield results; even a period of short as two or three weeks immersed in the target language will inevitably lead to improvements. Yet fluency is only one step closer to what should be the English language learners’ ultimate goal: mastery of English’s nuances, exceptions, and enormous vocabulary.