# reference to an array
my @employees;
my $employees_aref = \@employees;

# reference to a hash
my %records;
my $records_href = \%records.

# reference to a scalar
my $huge_text;
my $huge_text_sref = \$huge_text;

# This naming is popular in subroutine parameters.
sub calc_employee_salary {
    my ($employee_aref) = @_;
    # $employee_aref is a reference to an array 
    # holding employee IDs (or names, whichever)

   # since this is an array reference, use ‘@’ to get to the
   # actual  array. 
    foreach (@$employee_aref) {
    #  .  .  . 
    }
}