The Sun initially had a very many resources. And at the same time, it is not so much burning as it is smoldering: per unit volume, the Sun emits less energy than the human body. But the resources of the Sun are not renewed, so eventually (after about 7 billion years) it will go out.
Where does the Sun get energy from? From the reactions of thermonuclear fusion of helium nuclei by hydrogen nuclei in the central regions of the Sun at temperatures over 12 million degrees. Every second in the core of the Sun as a result of thermonuclear burning of 600 million tons of hydrogen nuclei, 596 million tons of helium nuclei are synthesized. The difference in masses (4 million tons per second) has been warming the Universe, including us, for more than 4.5 billion years.
The resulting helium, being heavier, settles towards the center of the Sun (like coal in a fire), pushing free hydrogen from the center of the Sun into the outer layers. A few billion years later, the thermonuclear combustion of hydrogen in the outer layers will lead to the inflating of the Sun and the transformation of the Sun into a Red Giant with a radius reaching the Earth's orbit. It will be hot, but the good news is we will be gone then.