Custom Search Filters (Form Setting)

You may add one or more custom filters to the search interface in a list by clicking the “Add Custom Filter” button and configuring the following settings:

• Custom Filter Name - Enter a name for your Custom Filter.
• Filter Setup - Use the Query Builder to define the search criteria for your custom filter. This query must end on the table that the list is showing.
• Default Sort - This will determine what order the the filters appear in the dropdown list.

See a video on this here