how to nest a php variable in string
Do it like this:
echo '<td><a href="product_description.php?id=' . $id . '" >' . $row['PropertyType'] . '</a></td>';
You should also think about echoing the data in the html, instead of echoing out html itself. It is a lot cleaner.
e.g. you can do the above like this:
<?php
// your php, ready up the data. your $id and $row
?> <!-- close your php tag -->
<td>
<a href="product_description.php?id=<?= $id ?>" >
<?= $row['PropertyType'] ?>
</a>
</td>
Note: that <?= $var ?> is equivalent to <?php echo $var ?>.