What part of a script instructs the actors on how to move or instructs about the movement of props

Stage direction.

Explanation:

Stage direction is a sort of instruction written on a script of a play that contains information about how the actors are to act, how the props are to be placed or moved and even the other effects of the scene. This stage direction provides the written instructions that will determine how and where the actors move, what sounds they are to make, how the lightning and settings are to be done etc.

These cues provide the characters about their performance, what they are to do and how they are to deliver their lines. These notations are indicated in the script by parenthesis, so as not to be verbally spoken out. Written in the perspective of the actors performing the act, these cues provide them guidelines about what and how they are to perform their parts.