Refers to a puzzle or riddle, often one that requires deciphering or interpretation. Can be used for word puzzles, rebuses, or enigmatic statements.
This puzzle is quite hard to solve.
His words are like a riddle.
From 判じ (はんじ, 'deciphering') + 物 (もの, 'thing'). The exact historical derivation is uncertain, but the word refers to something that needs to be figured out.