How will Prestashop know about all my products?

Prestashop is a flexible point of sale system. You can configure Prestashop directly so that it holds the information on all the products you wish to sell. OR....

If you are also using another app where you keep all your product information (product lists, price lists, catalogues, etc.), then you will benefit from Connec!™. 

Connec!™ automatically shares data between your different Maestrano applications. For example, if you use Dolibarr or vTiger on Maestrano and you have your products and prices loaded into that system, when you choose Prestashop and switch on sharing, your product will automatically be shared into Prestashop.