Understanding Emotional Context through Stage Directions

In a play, stage directions are essential for guiding the actors' performances and informing the audience about the setting and character movements. Consider the following excerpt from a fictional drama:

As the curtain rises, the room is dimly lit. [Nina enters from stage left, hesitantly glancing around before moving to the window.] The atmosphere is tense, and Nina's expression reveals a sense of uncertainty.

Based on this stage direction, what can be inferred about Nina's emotional state and the overall mood of the scene?