hi,
here is lines 90 of templates/purity_iii/html/com_contact/category/default_items.php:
<?php echo implode($location, ', '); ?>
php manual says:
implode(string $separator, array $array): string
If you look at joomla components/com_contact/views/category/tmpl/default_items.php you see:
<?php echo implode(', ', $location); ?>