Hey there! So diction basically means what words that the author uses. If they use certain words together, it can create the mood, which in this case is unease. An example might be using words like, "dark", "shadow", "creaking", "silence", or "creepy" in a horror/ scary story. When used together in the story, it can create the mood that something bad migjt happen. The author choses these words carefully to fit the passage. In otherwords, he would not use happy words if writing a horror story.
