Figurative language is used when a word or phrase does not have its original, literal meaning. There are many categories of figurative language. The ones you might notice the most are 'metaphor' and 'simile'. However, there are other ways of being figurative, including using 'personification', 'exaggeration' and 'understatement by using double negatives (litotes).
literal (adjective), literally (adverb)
When a word or phrase is 'literal', it represents exactly what it says. A literal word has its original, basic meaning, rather than a figurative meaning. Some phrases could be literal or metaphorical. For example, if someone says, "You're driving me round the bend," they might mean that someone else is irritating them a lot. This would be a metaphorical meaning. However, if they were sitting in the passenger seat of a car, being driven around a tight corner, they might mean 'round the bend' literally.
metaphor (noun), metaphorical (adjective), metaphorically (adverb)
A metaphor is an example of 'figurative language'. It is a 'figure of speech'. A metaphor is a word or phrase that describes an object, an event and action or an idea without being literally true. An example would be, 'The child's bedroom is a disaster area'. The bedroom isn't literally a disaster area (we hope).