na-adjective
happy-looking; cheerful; pleasant
Describes someone or something that appears happy, cheerful, or pleasant. Often used to describe a person's expression, atmosphere, or manner.
彼女は楽しげに笑った。
She laughed cheerfully.
楽しげな音楽が流れている。
Pleasant music is playing.
楽しい is an i-adjective meaning 'fun' or 'enjoyable', while 楽しげ is a na-adjective describing an appearance or manner of being happy or cheerful.
Formed from the stem of 楽しい (たのしい, 'fun') + the suffix げ (expressing appearance or manner).