Does prestashop have a database full of products, and you'd like the products in this xml file to be imported into the prestashop database? I'm guessing that's what you want. If so, you need a program (in some server side language like php) to read the xml file periodically (daily, weekly, etc) and load the data into the database.
You could do that yourself or hire someone to do it. It would involve knowing how to read through and xml file, and how to interact with the prestashop database.