Meaning: This sentence describes the river as a calm and tranquil entity, peacefully flowing through the valley.
Choice of Words: "River" is a natural stream of water flowing in a channel. "Flowed" means to move smoothly and continuously. "Calmly" means in a peaceful and undisturbed manner. "Valley" is a low area of land between hills or mountains. Together, these words suggest that the river is moving smoothly and peacefully through the valley.