Props are important in theatre because they help set the mood and help the audience know what’s going on. For example, using a lamp as a prop could mean- decoration, a weapon, or just helping to set the mood with ambient light. Without props, it would look like just a bunch of people running around; we, the audience, wouldn’t know what’s going on. (Don’t know how many words that is, feel free to word salad in a few sentences- just thought I could help you a little!)