The entry-list shows the configured labeling options. To start labeling click on an entry or press its shortcut (if a shortcut was defined).
Click on an entry or press the shortcut to start drawing the geometry. If there are classifications attached to this geometry, you will be able to answer them after you finish drawing.
To answer global classifications click on the "Show global classifications" button.
The entry shows a shortcut (if it has one) and an icon representing the geometry in the configured color. The number on the entry is the number of labels that have been drawn of this configuration.
Clicking on the "eye" icon will hide all drawn geometries in the workspace that belong to this entry. Click the icon again to show them.
The entry that is currently being drawn is marked by a dot in front of it.