number of words to understand a language How many words do you think you need to understand a language? And how many to speak it? Have you sometime asked yourself this question. I am reading books from a collection called Penguin readers and they are placed by levels. I am now reading books of level three and they have around 1200 words per book. I understand almost all of the words and I think I am going to try the next level that has 1700 words per book. I think it is a good way to improve slowly but effectibly the vocabulary.