A hyperbole is an exaggerated statement or claim that is not meant to be taken literally. My son likes to use hyperbole when he is hungry. "Dad, I am so hungry! When are we going to eat? I'm starving!" Of course I know it's hyperbole. I fed him 3 hours earlier. He's not literally starving.
In Edgar Allen Poe's story, "The Fall of the House of Usher," there are couple of statements that use hyperbole. The first one is from the opening sentence.
During the whole of a dull, dark, and soundless day in the autumn of the year, . . .
The day couldn't possibly have been soundless. That's an exaggeration of how quiet the day might have been, but unless the day is without an atmosphere, there is sound.
Another hyperbole from this story that teachers like to use is the following:
I looked upon the scene before me—upon the mere house, and the simple landscape features of the domain— upon the bleak walls—upon the vacant eye-like windows— upon a few rank sedges—and upon a few white trunks of decayed trees—with an utter depression of soul which I can compare to no earthly sensation more properly than to the after-dream of the reveller upon opium . .
The statement is an exaggeration that helps the reader understand just how incredibly bleak the scene looks. It's so bad that he can't find words to express the depression that he feels. He can't even compare it to anything that he has ever felt before. That's bleak all right.