This calls the named subroutine with two values: the string $Dut (which is not interpolated, because of the single quotes), and an array reference. The array reference points to an array with three values:

1. the string 'or'
2. an array reference pointing to an array containing one element, the string 'u'
3. an array reference pointing to an array containing one element, the string 'v'

When you understand that, you can figure out what the other two lines are doing.