Research: 180 Degree Rule

The 180° rule is a basic guideline in film making that states that two
characters (or other elements) in the same scene should always have the same
left/right relationship to each other. If the camera passes over the imaginary
axis connecting the two subjects, it is called crossing the line. The new shot,
from the opposite side, is known as a reverse angle.
- Wikipedia.

If the 180 degree rule is broken, then the film maker may confuse the viewer, as the characters or subject will have suddenly switched positions.

Here is a video by VideoMaker, illustrating the 180 Degree Rule.