This page is very similar to the parent Label Assignments page - it lets you assign labels via wildcards and filters. The difference is that they only apply in certain locations.
You can use the Add Folder button to add a specific folder, and Add Wildcard to specify a wildcard pattern that will match target folders. The list shows any folders you've configured, as well as entries for specific content types and folder types.
Select an entry from the list and click Edit to define its label assignments. See the Label Assignments page for more information on wildcard and filter labels.