The character 乐 (yuè) means "music" and is used as a short form or component in words related to music, such as 音乐 (music), 乐器 (musical instrument), and 乐队 (band). When pronounced yuè, it specifically refers to music rather than happiness.
他从小就学习民乐,特别喜欢二胡。
tā cóng xiǎo jiù xuéxí mínyuè, tèbié xǐhuān èrhú.
He has studied traditional Chinese music since childhood and especially loves the erhu.
这个学校的乐队在比赛中拿了第一名。
zhège xuéxiào de yuèduì zài bǐsài zhōng ná le dì yī míng.
This school's band won first place in the competition.
她会弹好几种乐器,最擅长古筝。
tā huì tán hǎo jǐ zhǒng yuèqì, zuì shàncháng gǔzhēng.
She can play several kinds of musical instruments and is best at the guzheng.