Most student complain not to be able to say any sentence while they’ve been learning and studying the language for years. It’s indeed not very motivating to keep studying!
So, why do I announce in the title that it’s possible to learn much faster? Actually, the answer is both simple and logical. Let’s dive into it!
A language, what is it? Mainly words. What students don’t seem to know is that you don’t just use one word only once. There are two kinds of words: frequent words, and infrequent words. Frequent words are used very often (I, you, be, have, but, eat, often, always, ..). These are words that people use in almost every sentence. They are often grammar words, verbs, … With about 500 words, it’s possible to understand about half of any movie (for written material, more is necessary). With 1000 words it’s possible to understand 75 to 80% of any text and close to 90% of anything spoken, and with 2000 words the figures go up to 85% of what we read and over 90% of what we hear, according to this source.
Still, the number of words needed to do certain things varies a lot, but you get the general idea 
Here is a list of the 100 most frequent words in English. Keep in mind that different websites and sources will give different data, but most words are the same.
Infrequent words are those that we often study at school, precise words, after working on the basic words. There words are nevertheless important because they’ll help you when going abroad. But you won’t find these words very often. You can thus use the language without knowing these words, but you will need them if you want to get going abroad in diverse situations.
In a nutshell, what should you remember of all this? First of all, study frequent words. You can easily find frequency lists by looking for the 1000 most frequent words of a language on google. If you learn 20 words a day, you’ll get to 500 words within 25 days, thus less than a month. If you do that for 100 days (3 months), you can read a newspaper (if you study well and revise enough)
Nevertheless, you need to learn these words in an efficient way. Ideally, you need to learn words in context, in a sentence. And don’t forget to train your ears so that they can recognize the words and reproduce them!
This whole explanation is a qualitative one: study intelligently, study quality words (which occur regularly), instead of thousands of words you’ll only use from time to time.
Last piece of advice: even with 500 words you can speak. When I say “speak”, I mean using easy sentences, get on with the language, but speak all the same. Try it, you might be astonished 😛