String Music
noun
Remember how 楽 was used in 音楽 (music)? Well this is that 楽 again. So this is string music, which of course means string music.
This is a jukugo word that uses the on'yomi readings of the kanji, and you've learned both. Just remember that 楽 uses its secondary reading がく when it's in music-related words!
学生時代に数年ほど弦楽をやっていました。
I played string music for several years during my school days.