What it is
Instead of only describing the task (zero-shot), you show 1 to 3 input and output examples. The model learns the format and style from them, right there, without retraining.
Why it matters to an agency
It is the fastest trick to raise the quality and consistency of a prompt: a couple of good examples usually gives the biggest jump in quality.
Example
Before asking "classify this message", you show 2 messages already classified as a reference for the exact format you expect.