A debt jubilee is a clearance of debt from public records across a wide sector or a nation. The first jubilees were during ancient times which were carried out by kings, sometimes administered on the basis of religious teachings, especially those religious laws which banned usury. This happened primarily after wartime so that debts of dead subjects would not transfer down to their descendents and reduce society's capability to recover from war. Because of the enormous impact of such debt cancellations on public prosperity, the occasion usually coincided with festivities and "jubilees".
Professor Michael Hudson has written frequently on this subject.[1]
The religious meaning of the term in the christian context specifically is that humanity had accumulated a debt to God through it's sins and that Jesus Christ repaid in our stead.