Nuance refers to slight and subtle differences in shades of meaning. Something that is nuanced has many different shades of meaning, in the same way that a photo might have many different shades of gray. An example is like imagining that a character in a novel is walking across the room. Think about how it would be different if that character marched across the room versus if that character shuffled across the room. So your answer would be that you have to pay attention to the way something is written!
