Debt service
The payments a town makes on money it has borrowed through bonds and notes, covering both principal and interest. Each year's budget must include a separate line for it.
New Jersey example
Made-up case: a town sells bonds to pay for a new firehouse. Every year until the bonds are paid off, its budget must include the principal and interest due. Debt service is an exception to the 1977 spending cap, and increases in it are excluded from the property tax levy cap.
Official source
This is a plain-English summary. Rules and dollar amounts change, so check the official source or a professional before you file or sign anything.