Quick filter, as the name itself says, is a type of filter you can quickly set-up in order to verify results on a selected number of cases or just because the filter conditions you would like to apply to your data are so simple that you don't need to follow the default path. The type of lanuguage to use to define quick filters is the same type of language and with the same rules to the one used to define formulas for calculated variables.

For example in Designer Window, you'll see the quick filter box in the 'Data file options' menu.

Just type in the desired formula, in this case I wanted to 'filter' for those who have both Country=1 AND ID>1

Once the formula is typed, the resulting table in Scrapbook/Workbook would be like the following one. In the bottom corner of the table, the description of the used filter is also automatically provided, as if you're using any other type of filter.