Comparative advantage
Suppose the number shows the number of hours required to create one piece of cloth or one crate of wine. In 100 hours, England can either make 1 unit of cloth or 5/6 units of wine. Meanwhile in 90 hours Portugal can make 1 unit of cloth or 9/8 units of wine. Portugal has an absolute advantage in both. However England's opportunity cost of 5/6 is lower than Portugal's OC 9/8. Hence England has a comparative advantage in cloth-making.