GDP is the total value of goods and services produced in a country in a particular time period. Fiscal Deficit is sometimes measured as a percentage of a nation’s GDP. Fiscal deficit is total revenue generated – total expenditure. It is the total money spent by the government of a nation in excess of the income generated by the government. You can read about the Fiscal Responsibility & Budget Management (FRBM) Act in the given link.

Further readings:

1. Previous Years Economic Mains Questions for UPSC GS-3
2. Indian Economy Notes For UPSC