I see it, you are targeting table rows, but each table only has one row.
If you need a single multi row table, you need to open the table before the while and close it after, so each database row creates a table row, not a new table.
<?php include 'connection.php';
$sql= "SELECT Name, Description, Price, Type FROM Treatments WHERE Type ='facials for all ages'";
$result= mysqli_query($con, $sql);
echo "<table>";
while($row=mysqli_fetch_array($result, MYSQLI_ASSOC))
{
echo "<tr><td><strong>" .$row['Name']. "<br></strong>";
echo $row['Description'];
echo "</td><td>";
echo $row['Price'];
echo "</td></tr>";
}
echo "</table>";
mysqli_close($con);
?>