Final answer:
When encountering a white and red light on another vessel at night, your vessel's role depends on whether the white light or red light is seen.
Step-by-step explanation:
When encountering another vessel at night and seeing a white and red light, your vessel's role is determined by the International Regulations for Preventing Collisions at Sea (COLREGS).
If you see a white light, it means the vessel is approaching you from the front or directly ahead. In this situation, your vessel needs to maintain its course and speed.
If you see a red light, it means the vessel is approaching you from the side or to your right. In this situation, your vessel needs to give way to the other vessel by altering its course to the right.