Prestashop Alphabetical Product Search is a module which adds a block of alphabets in your store front end. So when user will click on any alphabet the module will show all the products from your store whose name starts from the alphabet which has been clicked. It also shows the number of products present for each alphabet when make hover on the alphabet.
There is a powerful settings for the module from where you can change each option. You can also change the look and feel of the alphabets so that it will match your beautiful store.
There is also setting where user can see all those alphabets which has at least a product. You can also search all the products starting from numbers also. All those settings can be configured from the module backend.