Different parts of the world have different advantages in terms of natural resources, climate, etc. By focusing their economic activity to what they historically have done the best and most efficiently, parts of the world then would be able to trade these goods making everyone better off. This is the main thesis of what is called competitive advantage and what the author hopes free trade can exacerbate. Obviously the author, as a free trade advocate, does not mention the criticisms of free trade, one of which being that not all countries play by the same rules, for example human rights, therefore free trade doesn't provide the benefits promised in theory.