Headline growth figures are always real unless stated otherwise, because a 6% nominal expansion during 5% inflation is barely any growth at all. The conversion factor between them is the gdp-deflator.
Nominal GDP still matters in its own right. Tax revenue, corporate earnings and debt service are all nominal, so debt-to-gdp dynamics and the sustainability of government finances depend on nominal growth relative to nominal interest rates.
Example: nominal GDP is $29.0 trillion and grows to $30.7 trillion, up 5.9%. With a 3.3% deflator, real growth is 1.059 / 1.033 minus one, about 2.5%.
Related: gdp, gdp-deflator, gdp-vintages, debt-to-gdp, potential-gdp