弹

弹 is a two-reading character. As a verb read tán, it means to play a plucked or keyed instrument (弹钢琴 'play piano,' 弹吉他 'play guitar'), and by extension to flick, spring, or bounce (皮球弹起来, 'the ball bounces up'). As a noun read dàn, it means a bullet, shell, or projectile (子弹 'bullet,' 炸弹 'bomb'). The seed gloss lists the dàn 'bullet' meanings, but the HSK 4 entry is the verb tán.

English speakers should note that Chinese uses different 'play' verbs for different instruments: 弹 (tán) for piano, guitar, and other plucked/keyed strings; 拉 (lā) for bowed instruments like violin (拉小提琴); 吹 (chuī) for wind instruments; and 打 (dǎ) for drums. You never use the generic 玩 ('play, have fun') for playing an instrument. Register is neutral.