"Rōnyaku-nannyo老若男女" means "old and young, men and women" - referring to people of all ages and genders. "It's a comprehensive way to say "everyone" or "people from all walks of life." EX. このお祭り（おまつり）には老若男女（ろうにゃくなんにょ）の人（ひと）たちが参加（さんか）しました！ People of all ages and genders participated in this festival!