Refers to the petroleum fuel used in oil heaters, lamps, and similar equipment. In Japanese daily life it is especially associated with portable kerosene heaters in winter.
ストーブに灯油を入れた。
I put kerosene in the heater.
冬になると灯油の値段が気になる。
When winter comes, I start worrying about the price of kerosene.
I put kerosene into the heater.
We ran out of kerosene, so I went to buy some.
In winter I buy kerosene often.