Answer:
A subsidy, usually some money granted by the government, is meant to support a struggling or in- need industry. It allows an industry, say, farming, can thrive, at it is in the public's interest and farmers might need help.
Subsidies are supposed to be granted for the public, in the public's interest, but large grants of money have been given to, say, the fossil fuel industry for years and years now, and the fossil fuel industry (coal and petroleum mining, and burning for energy) are NOT in the public's interest.
Lots of government subsidies are disputable, but they are generally sums of money meant to support, or subsidize an industry.