A Section within Backstage where you can edit what search statistics are available to then use as a Filter for your users.
For example, a Facet is the results from a searchable attribute (e.g. Color) so you have 23 green items, 14 blue items and 12 red items. So if a user applies the Color filter on your website, you can display the results of your Facet by showing Green (23), Blue (14), Red (12).
Please note, the information that you input within this App can be overwritten by a Developer in the Catwalk so make sure you only pick one way of updating this (either using the Catwalk OR within the Facets App).
The image below shows the landing page within the Facets App:
"I''m using the Facets App to enable a new Filter category based on if our product is in stock or not so I can display the results to our users."