From the cgi.pm docs:
FETCHING THE VALUE OR VALUES OF A SINGLE NAMED PARAMETER:

    @values = $query->param('foo');

              -or-

    $value = $query->param('foo');
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Pass the param() method a single argument to fetch the value of the named parameter. If the parameter is multivalued (e.g. from multiple selections in a scrolling list), you can ask to receive an array. Otherwise the method will return a single value.

HTH