Figurative Language can be used to communicate theme and many other things for many reasons, but the goal of figurative language is always to clarify.
Figurative language refers to the method we end up using to amplify our own writing or even speaking and it takes an ordinary statement, that many times can be ignored, or perceived as uninteresting, and turns it up in an evocative frock. It discretely alludes to something without actually saying it. Figurative language is just one more way to engage and excite readers, ushering them through your writing with a more creative way of conveying tone or theme.