겹쳐요 · 겹쳤어요 · 겹칠 거예요 · 겹치세요
to overlap; to coincide, clash (schedules); to pile up
Example
두 수업 시간이 겹쳐서 하나만 들을 수 있어요.
The two class times overlap, so I can only take one.
Word parts
From 겹 (layer, fold): things lying layer on layer.
Good to know
Also used for bad luck piling up: 불행이 겹치다 (misfortunes come one after another).