To help users narrow the search results that display when they're looking at assets in the public portal view, portal creators can add up to five filters to each asset and collection section within the portal in the Live Editor. Filters are the controlled metadata fields available in the Assets app. The fields that can be selected in the Live Editor, and that then display in the public view, are based on the portal creator's permissions.
To add filters, click the Settings (gear) icon for the section, then select Filters. In the filter settings, choose to enable filters, which means they'll display for those who can view the portal. Once enabled, select the filters you'd like users to see from the dropdowns that display.
In the public view, users can then choose from those filters to easily narrow down their search results.
Note that filters display in the public view of the portal only if there are assets associated with controlled metadata fields. However, portal creators will see all filters in the Live Editor and in the public view.