It is not a surprise that English words has roots in Latin and Greek. In fact, over 60 percent of English words have Latin or Greek root words. So as you see, knowing of Latin and Greek roots can bring you enermous benefits. 
First and foremost, by knowing one Latin or greek root of the word allows you to understand meaning of oher words with the same roots.So you dont have to look up words in the dictionaries you just can guess the meaning.
Sometimes, knowing the ending of the word can help you identify the part of a speech of a word, which can help you know how to use it in a sentence.
As Latin and Greek roots are the same in every language, knowing them can be beneficial for you to learn not only English but other languages too with remarkable ease.
Text - Unit 5 p90 -91