忙 is built from the 忄 (heart (left)) and 亡 components.
It reads モウ like 亡, as do 望, 盲, 妄, and 忘 — learn 亡 once and the family's reading comes with it.
A common word using 忙 is 忙しい (いそがしい), meaning “busy (people, days)”.
Kanji that look similar include 快, 怖, 性, and 怪.