In the filter field, you can put in a value and only those form records that match the value is displayed. If you put data into more than one filter field, only the records that pass all the filters are displayed.
In addition to putting in a value, you can also prefix the filter value with an operator (=, !=, <, <=, >, >=) to do comparisons other than equals.
For example if you put <2020 this will compare the field and only display records that contain a value less than 2020.
Filters can use the power of regular expressions to do complex, but powerful pattern matching. Regular expressions are of the form /expression/ . A simple example is to search if a string is contained in the field. For example, if you are looking for all forms that have the word jim in a particular field, you could enter the filter /jim/ for that field.