Contextual Clues and Idioms

I've learned in our subject is about Contextual Clues and Idioms, Contextual clues it is a source of information about a word that helps readers understand the word. This word or phrase offers insight, either directly or indirectly, into the word’s meaning, while the Idioms is a word or phrase that is not taken literally  like “bought the farm” has nothing to do with purchasing real estate, but refers to dying. For me this two topics, it can help us to know more better meaning of one sentence that we cannot understand.