Weirdly, I figured out the SRCA modality when I did improv classes. It just suddenly clicked. So this is my non-definition way of explaining it.
Setup - The base reality of the scene. (Who, what, where?)
Revelation - The inciting incident. (Something unusual happens that drives the scene)
Conflict - The conflict that surfaces after the inciting incident. (An exploration of the conflict of the scene)
Aftermath - The resolution to the conflict. (The conclusion of a scene, or the lead into another scene)
So, a dumb example I made up quickly without any thought:
Setup - A dentist goes to a cafe with his wife. They're discussing their divorce settlement.
Revelation - The dentist is deathly afraid of sugar cubes.
Conflict - The dentist's wife begins using the cubes to blackmail him into giving into her demands.
Aftermath - The dentist signs the settlement.