The U.S. current account is the broadest measure of trade and income flows between the United States and the rest of the world. Together with the capital and financial account, it is a component of the international transactions accounts compiled by the Bureau of Economic Analysis.
The current account records exports of goods and services (for example, wheat shipped from the United States to Russia or legal services provided by a U.S. firm to a client in Japan) as well as receipts of income on U.S.-owned assets abroad (like income earned by a U.S. company from a plant it owns in Canada). Then it subtracts imports of goods and services, payments of income on foreign-owned assets in the United States, and unilateral current transfers (such as gifts to other countries) to come up with the current-account balance. In 2011, the United States had a current-account deficit of $465.9 billion.
Components of the current account can be used to monitor major developments in the U.S. economy. All of its components are included as part of the foreign sector in the estimation of the national income and product accounts—the gross domestic product.
The current account in many ways is similar to an income statement for the entire economy. For example, exports are similar to businesses generating receipts from the sale of a good or service. Income receipts are similar to businesses generating income from dividends or interest. And unilateral current transfers are like grants a company might make or gifts it might receive. This aggregation over the entire economy provides a useful glimpse of current international economic transactions over a period of time.
You can read more detailed information about the current account here and here.