Meaning: This sentence is describing how music can create a sense of peace and unity in a space.
Choice of Words: The word "harmony" is a noun that refers to the pleasing combination of different musical notes. "Fills" is a verb that means to make something full. "Room" is a noun that refers to a space within a building. When you put these words together, you get a sense of the way that music can create a beautiful and peaceful atmosphere.