I tried to enable the joomla debug mode in my website and discovered that JoomSEF is generating the keywords and descriptions (I extracted part of the debug output and pasted on the previous message), but for some reasons the keywords and description is not available on the browser (and probably for the search engines).
If you open the website, acces one of the products page and visualize the source code of the page you can see that the description and keywords meta tags are replaced by "La Fonte S.r.l. Official Site" the default I set in Joomla CPanel.
I also tried to leave empty the default tags but the result is that they are empty on the pages too.
I replied to the post related to the sh404sef uninstallation because in effect I had this component before to install JoomSEF and I have the mentioned table in my DB.
I thought that it could have caused this behavior so I was wondering if it was possible to remove it without reinstalling JoomSEF.
Hope to have been clear enough