question about how echo?

Question

i am studying for a final (about waves)
and i don't understand the concept of echo.
for example the question would be:
f you yell or clap your hands while standing at the edge of a large rock canyon, you may hear an echo a few minutes kater. Explain why this happens.
*and i would have no clue what to write for the answer

Answer 1

The sounds waves bounce off the rock and come back to you a bit later.