English has a large vocabulary with an estimated 250,000 distinct words and three times that many distinct meanings of words. However, most English teachers will tell you that mastering the 3000 most common words in English will give you 90 to 95% comprehension of English newspapers, books, movies, and conversations. In addition, with that size of a vocabulary, you'll easily be able to learn from context to expand your vocabulary as you go. The important thing is choosing the right words to learn so you gain comprehension quickly and don't waste time.