If aggregate demand (ad and nominal gdp (gdp increase while the price level is constant, we would conclude that:

An increase in aggregate demand indicates a good economy having low prices of goods that are consumed by the people. Low unemployment rate and a well-managed government expenditure is part of an increase in aggregate demand.

The gross domestic product on a nominal basis is the total economic standing of a country an increase would tell that there is a significant improvement in the economy.

If the aggregate demand is increasing while the price level remains constant, it means that the spending and consumption in a macroeconomic setting is increasing. Given the constant range prices, consumers are now able to spend more therefore pushing the demand higher.