Real GDP is calculated using a GDP price deflator, which is the difference in prices between the current year and the base year. Then nominal GDP (GDP adjusted for inflation) is divided by this deflator, yielding real GDP. Nominal GDP is usually higher than real GDP because inflation is typically a positive number.
Since GDP measures an economy's output, it is subject to inflationary pressure. So real GDP is a measure of an economy's output adjusted for inflation.
Last quarter South Korea real GDP was 571.647 T KRW, and the quarter before that it reached 572.951 T KRW.