too put it simply, international trade is an act of exchanging economic products through the activities called imports ( buying a product from other country) and export (selling product to another country).
The amount of total import and export will affect the Balance of trade of the country, which is a difference of the amount of that country's import and export
in an international trade some countries can produce a specific product more efficiently than other products in that country , which called and comparative advantage, and more efficiently than other countries, which called absolute advantages
hope this helps