Hi nicolafw,
OK, so I can see you're not too proficient with PHP. If you want to use it in your current code, use the following:
<?php // Product Short Description
if(!empty($product->product_s_desc)) {
$product_s_desc = str_replace( "\n", '<br />', $product->product_s_desc );
echo shopFunctionsF::limitStringByWord($product_s_desc, 300, '...');
}
?>
I hope this helps.