Words are an important part of languages
When learning languages, the words are important part of it. If the words are unknowns, nothing can be understood, nothing said, nothing written, nothing heard and nothing read. After all, language is the use of words.
They are like the pieces of the puzzle. If one piece is missing, it is not a problem. No matter what kind of picture, it can still be seen. But when there are a lot of pieces missing, it is hard to know, what is draw on it.
The languages are the same. If there is one or two words that are unknown, the meaning can still be understood. But when half of the words are unknown, then the message can not longer be understood.
That is why the words are extremely important when learning languages.