夏 (なつ) means "summer," the warmest season of the year. You can use it to talk about summer activities or tell someone that you like or dislike summer. For example, 日本の夏は暑いです。(Nihon no natsu wa atsui desu.) means "Japanese summers are hot."

夏（なつ）は一年のうちで一番暑い季節です。「夏が好きです」のように使います。