RewriteEngine On
RewriteRule ^products\/(.+)$ index.php?action=products&product_id=$1
You will have to change your PHP script so that it finds the product by name. If you don't want to do that, you can pass the ID in the URL along with the name. Like this for example:
Code:
RewriteEngine On
RewriteRule ^products\/(.+)-([\d]+)$ index.php?action=products&product_id=$2