In not knowing the configuration of the lights you are looking at, it is hard to answer. If the red light is lower on the vessel around the bridge, you maybe seeing the vessels port side (left) running light. The white light is going to be either a masthead light or possibly a stern light. However if the red light is much higher, atop the mast, then this could indicate more than a few different scenarios.
Lights & Shapes
Rule 21-International
Definitions
(b) "Sidelights" means a green light on the starboard side (right) and a red light on the port side (left) each showing an unbroken light from right ahead (000 degrees) to 22.5 degrees abaft of the beam on its respective side. In a vessel of less than 20 meters the sidelights maybe combined in one lantern carried fore and aft of the centerline.
You are approaching a sailing vessel - head-on
You are approaching a powerboat head-on
You are approaching a powerboat head-on
You are approaching the starboard side of another vessel
You are approaching a powerboat head-on
In maritime navigation, visible white lights indicate a vessel's masthead light or stern light, while green lights signify the starboard side of a vessel. When encountering another vessel in darkness, if you see a green light, it means the vessel is approaching from your right side. Conversely, a visible white light could suggest that you are either approaching the stern of the vessel or that it is facing you. Understanding these light signals helps in determining the direction and movement of nearby vessels to avoid collisions.
A visible white light on another vessel indicates that it is approaching you head-on. This means you should also exhibit a white light to signify that your vessel is also approaching head-on.
You are approaching the port side of another vessel
You are approaching the stern of another vessel
The other vessel is coming directly toward the observer, so both the port and starboard running lights are visible.
The other vessel is coming directly toward the observer, so both the port and starboard running lights are visible.
A visible white light on another vessel in darkness typically indicates that the vessel is either at anchor or is a power-driven vessel underway. In the context of maritime navigation, a white light can signify the stern of a vessel when it is moving away from you. It's essential for mariners to understand the configuration and visibility of navigation lights to determine the type and status of nearby vessels. Always maintain a safe distance and be prepared to take evasive action if necessary.