The is the difference in value between what a nation imports and what it exports over time.

Balance of trade.

Explanation:

The balance of the trade is represented by the net imports and the net export and is thus a difference between the nation's monitory values of money and is expressed as the exports and the imports over a certain periods and is thus take and the entire economy of the country as the more of the excess of the imports and less of the exports of a nation will lead to the economic deficits.