The trade balance figure is simply the difference between the amount of exported and imported goods and services for the reported month.
If the trade balance is positive, it means that the economy is doing well and the trade balance is in a state of surplus. A negative trade balance (deficit) reflects badly on the economic processes, on the exchange rate of the national currency, on trust and creditworthiness of the country. Trade balance is measured directly in monetary units of the country in which this indicator is released. Accordingly, New Zealand's trade balance is measured in New Zealand dollars.