桟 is built from the 木 and 戋 (small / narrow (in 浅·銭)) components.
It belongs to a phonetic family with 銭, 浅, and 践 — they share the 戋 component and the reading セン.
A common word using 桟 is 桟橋 (さんばし), meaning “wharf, jetty, pier”.
Kanji that look similar include 栓, 栞, 校, and 株.
