Hello,

The traditional modes of discourse is a fancy way of saying writers and speakers rely on four overarching modes: Description, Narration, Exposition, and Argumentation.

Exposition:  Exposition has many supporting and clarifying modes of discourse. It is the kind of writing that is used to inform.

Description:  Description tells what things are like according to the five senses.

Argumentation:  The purpose of argument is to convince through logic.

Narration:  Narration is story telling. It involves relating a series of events, usually in a chronological order.

Hope it helps.

Good Luck!