Mode refers to the function of the text. What is that text doing for the writer or audience? What type of information does it contain? Rhetorical modes have long been identified and used in Speech and Writing. Rhetorical modes may be used in Fiction, as well as those Fiction modes specific to storytelling.

Rhetorical Modes:

Argumentation - aka Persuasion - used to argue or persuade an audience to agree with a particular opinion or to take action based on that opinion, such as in a speech given in a court of law, or during a political debate, or to sell a product.

Exposition - used to explain a set of facts or a process, such as in a presentation on a researched topic, or a newspaper article.

Description - used to visually describe a person, place or thing, such as in a poetic verse, an auction catalog, or a travel guide.

Narration - used to relate a story or series of events, such as in an anecdote, a biography, or fiction.

Fiction Modes:

Action - the text that represents actions within the story. Lots of verbs here.

Conversation - aka dialogue - the text that represents reported or directly quoted speech within a story.

Description - pretty much the same as in rhetorical use; the text that describes how things, people, or places look or what they are like. Adjectives frequently used here, as well as figurative language.

Emotion - text that represents character emotion within a story.

Exposition - similar to its use in rhetoric, text that explains something. In fiction, it is often used to explain relevant background information.

Introspection - aka thoughts - text that represents the internal thoughts or monologue of a character.

Narration - a subset of rhetorical "narration";  the text which represents what the narrator of a fictional work is telling the audience. In movies and television, it's sometimes presented as a voice-over.

Recollection - text that represents recalled or remembered information or events. May be used with flashback or backstory.

Sensation - text that represents the senses, perception, or sensory details. Include references to sight, smell, taste, touch, hearing, but also senses such as temperature, pressure, movement,  or body position.

Scene -  all the text that represents one instance of conflict within a story, including any goal and obstacle.

Summarization - text which summarizes events in a story, sometimes used to cover time-frame shifts or to relay events less important to a plot.

Transition - text that transitions or signifies change within a story, including changes between modes, time-frames, settings, perspectives, scenes, etc.