In Freytag's Pyramid for short stories, the exposition is where we get to know the characters, setting, and initial situation. For example, in a adventure short story, it might introduce the brave hero in his ordinary world. The rising action then takes the hero on a series of challenges that increase in intensity. The climax is the most dangerous or exciting moment, like facing the big bad villain. The falling action is how the hero recovers from that moment, and the resolution is how his adventure ultimately changes him or his world.
The key elements are exposition, rising action, climax, falling action, and resolution. Exposition gives basic info. Rising action builds suspense. Climax is the peak. Falling action eases the tension. Resolution ends the story.