Idiommetaphor. Only people who are very good at speaking English will know what an idiom means in a sentence.
There are about 4000 idioms used in American English, and at least as many in British English. To even explain what they mean requires about 2000 words of defining vocabulary. This is about the same as the most complex Simple English we use here, which is between Basic English (for the simplest articles) and 2000 words (which definition of an idiom requires).
An example of an idiom would be 'break a leg' which means to put so much into something that you hurt yourself, or to 'shed crocodile tears' which means to seem sorry for something when in fact you arn't.