The Named Filter function allows you to provide at design-time a predicate that will evaluate each time the filter is run.
You create it in Predefined Config.
You provide the actual Predicate Function in Advanced Options.
To apply a Named Filter that has already been created click on the filter icon in the column header and select the Named Filter from the Filters list
The name that you give to the Named Filter is what will appear in the Column Filter dropdown and in the Query Builder in future so make it as succinct but descriptive as possible.