Several parts combine into one character.

丸 is read as a person bending their body into a round shape, or a round thing rolling down a slope. Either way "round, a round pellet" is its core sense. One account sees it as 仄 (to lean) reversed, showing a round thing rolling.

Korean hanja-sound "hwan": 丸藥 (hwanyak, a pill), 彈丸 (tanhwan, a bullet), 砲丸 (pohwan, a shot / cannonball), 淸心丸 (cheongsimhwan, a calming herbal pill). A round-shaped herbal-medicine pellet is called 丸 (hwan).

Mandarin: wán, 2nd tone. 丸子 (wánzi, a meatball / round dumpling), 药丸 (yàowán, a pill), 肉丸 (ròuwán, meatball), 鱼丸 (yúwán, fish ball). In Chinese and Hong Kong cuisine a round-shaped ball is called 丸子.

Japanese: on-reading ガン (gan), kun まる (maru) and まる.い (marui). 丸 (maru, a circle), 丸い (marui, round), 弾丸 (dangan, a bullet), 日の丸 (hinomaru, the Japanese flag), 丸太 (maruta, a log). There is a Japanese tradition of adding ~丸 (maru) to ship names and old castle names — 日本丸. Also, in Japanese the full stop (。) is called 句点 (kuten) or maru.

Memory aid: a body bent into a round shape — a round pellet, a circle.