壇 is built from the 土, 亠 (lid), 亶 (sincere (in 壇·檀)), and 旦 components.
It reads ダン like 旦, as do 担 and 胆 — learn 旦 once and the family's reading comes with it.
A common word using 壇 is 花壇 (かだん), meaning “flower bed”.
Kanji that look similar include 壁, 壊, 壌, and 墜.
