Storyboading question_What is slugging and how do you use it?

Hello, I am an armature artist studying storyboarding by myself.
In storyboard pro - panel window, there is a text legion called Slugging. What is this slugging? How do you utilize it?
I searched google, of course, but I still can’t understand what this exactly do.

Please help me!

Slugging: Add notes referring to the timing of the storyboard. Slugging is the timing of the individual
recorded lines of dialogue against the board.

in Toon Boom Storyboard Pro user guide pdf file.

There are several fields which are collectively known as panel captions. Captions are a method by which you can
organize information in your project, and tie that information to a panel. They are fully customizable. These are
the default names:
l Dialogue: Type or copy/paste dialogue from your script that occurs during this shot in the current panel.
l Action Notes: Type or copy/paste notes related to the action occurring in the panel.
l Slugging: Add notes referring to the timing of the storyboard. Slugging is the timing of the individual
recorded lines of dialogue against the board.
l Notes: Add anything relevant about the current panel or the shot it represents. For example, the crew
working on the shot, required props, ambient sounds, continuity notes or required equipment to complete
the shot.