Meaning: This sentence poetically describes the movement of waves as if they were engaged in a graceful dance.
Choice of Words: This sentence uses figurative language to create a sense of movement and grace. "Waves" are bodies of water that move in a rhythmic pattern, "danced" suggests the graceful and rhythmic motion of the waves, "upon" indicates their location on the water's surface, and "water" refers to the liquid that covers much of the Earth's surface.