Theme is basically just the topic or subject matter of something. Theme basically is referring to the main idea or moral of a story or any type of writing. Here is an example. "Rosie didn't know what to do. She accidentally broke her mom's priceless vase. She honestly didn't know if she should tell her mom the truth, or lie and pretend she didn't know about it." The theme of this would be conflict, or choosing good or bad. Hope I helped!