Meaning: This sentence describes the appearance of the children's cheeks, highlighting the effects of the cold weather.
Choice of Words: "Cheeks" are the fleshy parts of the face below the eyes. "Rosy" means pink or red in color. "Cold" means having a low temperature. "Weather" refers to the state of the atmosphere at a particular time and place. When you put these words together, you get a picture of the children's cheeks being pink or red from the cold weather, which is a common sight during winter.