Idioms are phrases that do not make literal sense but have understood figurative meanings. Examples provided are "face the music," which means accepting the consequences of one's actions, "smell a rat," which means having a suspicion of something wrong, and "go to the dogs," which refers to something declining in quality or efficiency. The document asks the reader if they have seen idioms used in media and if so, how they were able to understand the figurative meaning from context.