Hi @hs1972,
You can use WP_Query to get the total post. It should be something like this:
<?php
$args = array(
'posts_per_page' => 5,
'post_type' => 'product_custom_post_slug',
);
$myquery = new WP_Query($args);
echo "<h2>Found: $myquery->found_posts</h2>";
?>
To learn more about WP_Query, please take a look at this page: https://codex.wordpress.org/Class_Reference/WP_Query. If you have a further question about this, please ask WordPress forum.
Hope this helps.
