Even a powerful ruler can be shaken by a dream he cannot understand, so he looks for someone who speaks the language of images. Dreams do not use plain words. They speak in pictures, and those pictures carry meaning the waking mind has not yet grasped.
The one who reads dreams is not a magician with secret powers. He is simply someone willing to sit with the strange picture and ask what part of the dreamer it belongs to. A dream comes from the deeper layer of the mind that sees what daylight thinking misses. Bringing its message into ordinary words is how a person learns what is really happening inside them.