Fire district tax
A tax on property inside a fire district, a separate local unit run by elected fire commissioners to provide fire protection. Your town assesses and collects it with your other property taxes, then pays it over to the district.
New Jersey example
Say your township has two fire districts and your home is in District No. 2. Your bill includes District 2's tax, figured on your assessment. Districts that hold their election on the third Saturday in February let voters there decide how much the district raises. Other districts hold their election with the November general election.
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.