It is a method of accessing data in different ways e.g getting a record from a database by specifying any of x field values. There will be x subroutines all with the same name and which one the VB system uses depends on what you entered. Biggest advantage is that you simply enter a field value and never specify what field it actually is. Another record can be obtained using the same input box but now you specify a different field value to find.
You could get exactly the same result by having x possible inputs with a check box against each. You would then have to code to determine which check box was ticked, the data supplied and then either call one of x subs all with a different name or use x IF or CASE statements to get the record with the field value specified.