The word “happy” is an adjective.
Adjectives are words that describe or modify nouns, providing more information about the people, places, things, or ideas they refer to. In the case of “happy,” it describes a feeling or state of being, typically used to express joy or contentment. For example, in the sentence “She felt happy after receiving the good news,” the word “happy” describes the noun “she” and gives us an understanding of her emotional state.