The right side of the vessel is the starboard side, the light is green. The light is coordinated to the starboard side of the vessel no matter how you look at it.
Refer to Rule 21 of the 72 COLREGS, a link is provided below.
Starboard (right side).
The head and starboard side of the vessel is toward you
The head and starboard side is toward you
you are following another vessel on it's starboard side. the stern light and stbd running light are visible
All vessels at sea use a red light on the port side (left facing forward to front of vessel), and a green light on the starboard side (right).
Red marks the Port or left side. (Green is Starboard or the right-hand side.) Port
You are looking at the Starboard (right) side of that boat. If it is moving, it is moving to the right.
Green
The starboard side of a boat has a green light at night. According to maritime navigation rules, the green light is visible from the right side of the vessel when facing forward. In contrast, the port side, which is on the left, has a red light. These colored lights help other vessels determine the direction in which a boat is heading.
A green light is on the starboard side of the vessel. So it may mean that the starboard side is directly facing you.
During nighttime transit another boat's lights show: Green - the right, or starboard side, of that vessel; Red - the left, or port side, of that vessel; White - the rear of that vessel. The vessel is heading directly toward you
Seeing only a green light on another boat at night indicates that the other vessel is either a sailing vessel under sail or a powerboat that is approaching you from your port side (left side). According to maritime navigation rules, the green light is positioned on the starboard (right) side of the vessel. You should maintain a safe distance and be prepared to maneuver to avoid a collision.