Final answer:
When a train operator approaches a home signal displaying three yellow lights, they should slow down and be prepared to stop at the next signal.
Step-by-step explanation:
When a train operator approaches a home signal displaying three yellow (amber) lights, they should be cautious and slow down. Yellow lights on a home signal indicate that the next signal is red and the train should be prepared to stop. This is a safety measure to prevent accidents and ensure the smooth operation of the train system. The train operator should follow the signal and reduce the train's speed accordingly.