The balance of trade refers to the difference between the goods that are being exported with the goods that are being imported from different countries. Balance of payment refers to the inflow and outflow of foreign exchange. The country may sometimes need to borrow money from other countries so that it will be able to pay for the different imports that it needs from other countries.
This explains why the balance of trade and balance of payment are related to each other. Countries would need to know these things so that they can continue trading with other countries and at the same time, export their products to interested countries too.