Trade policies role in economic growth is very important, trade policies offers countries competition and wide range of choices. Trade includes exports (are produced goods and services of the country and sales to foreign countries) and imports (the goods and services you get or avail that produce and sell by other countries) in line with this trade gives economic growth because the more output produce will increase your Gross Domestic Product (GDP means total market value of all final goods and services produced within a given period within a country) and Productivity. It is should the net exports equal or must relatively good when positive or exports is high than imports, you can get it from calculating exports minus imports or what we call the rest of the world.
It is also important in trading to know where you can get best advantage or comparative advantage where in for example two countries trade a specific good, it is important the countries knows where or what good to specialize and can get maximum satisfaction and income. Trading is very important not only economic aspect but also in environmental relations of countries and partnerships, it is also gives implication to producers to produce at best and extensively to meet the standards of the global market, competition takes place and consumers has wider range of choices but the government should always do its role on protecting small markets, time to make them competitive and some rules on tariffs, quotas and restrictions to protect the domestic market as well.
Trade relies not only on countries participating, the rules and restrictions but also on exchange rates which varies, given for example Japan exports electronic gadgets at 500 yen or amounting of $300 and USA produces wheat and ...