Boolean fields are also referred as Yes/No fields, or True/False fields.
You can filter boolean fields with the is or is not operator.
For example, the filter below will match only the rows whether the Delinquent field has a value of 'Yes' (True).
Some fields are let you choose the special value Unknown, which signifies that the row doesn't have any value. In other words, it matches rows for which the field's value is blank / empty / NULL.