A predicate adjective is an adjective that follows a linking verb and describes the subject of the sentence. It provides more information about the subject by indicating a quality or state. For example, in the sentence "The flowers are beautiful," the word "beautiful" is the predicate adjective that describes the subject, which is the flowers. Predicate adjectives are essential for adding detail and depth to sentences. They help convey emotions, characteristics, or conditions. In the sentence "The sky looks gray," "gray" serves as the predicate adjective, giving us insight into the state of the sky.