Research 180 Degree Rule

The the 180° rule is a basic guideline that states that two characters 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.

If you can imagine an actor walking or running in a direction then you can picture the path they are following as a line. If two actors are talking to each other then draw a line to connect the two places where they are standing and extend the line in each direction to the edges of the set. Even if there are many actors in the scene you can still draw a line connecting the two opposing sides of the action.