It means deciding the topic. Is it about the calender, academic performance or others.

University of Michigan - Ann Arbor

1. domain classification
2. intent determination
3. slot filling

Main Components Extracted by Frame-based Dialogue System

An on-going but a helpful book resource about NLP
https://web.stanford.edu/~jurafsky/slp3/

It decides what general task or goal is the user trying to accomplish?

It extracts the particular slots and fillers that the user intends the system to understand from their utterance with respect to their intent. 