If an increase in income levels in Country A leads to a rightward shift in the aggregate demand curve for Country B's goods, it can be concluded that Country B will experience a corresponding increase in its overall economic output.

When people in Country A earn more money, they tend to buy more goods and services, including those from Country B. This increase in demand from Country A causes the aggregate demand curve for Country B's products to shift to the right. As a result, businesses in Country B will need to produce more to meet this higher demand, which can lead to an increase in overall economic output. For example, if Country A starts buying more cars from Country B because people have more income, Country B's car manufacturers will produce more cars, hire more workers, and boost their economy. Therefore, the increased income in Country A positively affects the economy of Country B through higher demand for its goods.