You can safely assume since Amazon is a US company we're talking about US pizzas, where a single pizza serves 3-5 people. Also, it's typical with American pizza to serve sides such as salad, garlic bread, pasta, fries, etc. and beverages, dessert so "2 pizza" can be read as "2 pizza plus usual sides".
> Domino’s large pizzas are the perfect answer to feeding a hungry group. These 14-inch pizzas feed approximately three to five people
> Domino’s large pizzas are the perfect answer to feeding a hungry group. These 14-inch pizzas feed approximately three to five people
https://www.dominos.com/en/about-pizza/sizes/large/