郊 is built from the 交 and 阝 (hill (left) / village (right)) components.
It reads コウ like 交, as do 効, 較, and 絞 — learn 交 once and the family's reading comes with it.
A common word using 郊 is 郊外 (こうがい), meaning “suburb, outskirts”.
Kanji that look similar include 効.
