A prolepsis within a narrative is typically a moment in which the story jumps forward to future events as a way to show what will occur. This is often done to provide the audience with information or to show scenes that would not otherwise be depicted, since they often occur outside of the story's timeline. The term can sometimes be used synonymously with the idea of foreshadowing, though this is typically seen as be a more subtle concept. A prolepsis can also be a rhetorical device used in debate, in which someone presents a point against their own argument and then provides evidence to discredit it.
Also called a "flashforward," a prolepsis within a story is basically a jump in time ahead to a future events within the world of the story. This is different from the natural progression of the storyline forward because it is a single event that is often sudden and of fairly brief duration. A television show, for example, might have a five minute prolepsis in which the audience is shown events that happen 10 years after the events of the show. Those things depicted in this type of jump are usually actions that will not be shown in the natural course of the narrative.
In some contexts, a prolepsis can be seen as similar to foreshadowing, or used to accomplish the same task, though it is often much more abrupt. Foreshadowing is typically a hint of events that are still to come in a story, usually those that will happen within the narrative. If a character is going to die by the end of a story, then events may be shown that suggest or hint at this to the audience. A prolepsis can be used in a similar way, by showing events that will happen after the narrative, to suggest things that must logically occur beforehand.
The term "prolepsis" can also be used as a synonym for "procatalepsis" which is a rhetorical strategy often used in debates or arguments. In this context, it refers to a technique by which someone presents an argument against his or her own point, in order to refute it. A person arguing in favor of gun control, for example, may bring up a statistic regarding police response time, and then present evidence to indicate how this has no bearing on the right to use firearms. This type of prolepsis is a popular way to throw off opponents during a debate, since it allows someone to present and refute elements of their argument before they do.