Her face is sun-burned after playing at the beach all day.

sun-burned 是由 sun（太阳）和 burned（burn 的过去分词，表示"灼伤"）组成的复合形容词。sun-burned 指"被太阳晒伤的"，形容皮肤因长时间暴露在阳光下而发红甚至脱皮的状态。