Which element of drama tells the actor what to do?

The element of drama that tells the actor what to do is the "stage directions." Stage directions are written instructions in a script that describe the physical actions, movements, and expressions of the characters, as well as the placement of props and set pieces on the stage. These instructions are usually indicated in italics or enclosed in brackets and are intended to guide the actors, director, and other production team members on how to bring the play to life. For example, a stage direction might indicate that a character should enter from stage left, pick up a pen from the desk, and begin writing a letter while pacing back and forth. Actors use these stage directions as a roadmap to bring their characters to life, and to help create a cohesive and believable performance for the audience.