On the ops desk the CY is where an export container must be gated in before the CY cut-off to make its intended vessel, and where an import container waits after discharge until the gate-out that ends its terminal storage. The yard works with whole containers moving under a single booking; a sealed box arrives, is stacked, and leaves intact, with the cargo inside untouched. The term to keep it apart from is the CFS (container freight station), which handles loose LCL cargo from several shippers being stuffed into a shared container at origin or stripped out of it at destination, while the CY only ever handles the full container itself.
Glossary
Container Yard (CY)
The area within a port terminal or container facility where full containers are received, stacked, and delivered, holding export boxes until they are loaded onto a vessel and import boxes after discharge until they are picked up.