Answer: The Sun's core generates energy through nuclear fusion, specifically the fusion of hydrogen nuclei (protons) into helium nuclei. This process releases a tremendous amount of energy in the form of light and heat, which is what makes the Sun shine.
The current estimate for the age of the Sun is about 4.6 billion years, and it is currently in the middle of its main sequence phase, where it is burning hydrogen into helium in its core. It is estimated that the Sun has been in this phase for about 4.6 billion years, and it will continue to burn hydrogen in its core for another approximately 5 billion years, based on our current understanding of stellar evolution.
So, at the present rates of energy generation in the Sun's core, it is estimated that the Sun will continue to generate energy for another 5 billion years. However, it is worth noting that as the Sun ages, it will gradually evolve and change, eventually entering a phase of expanding into a red giant, and ultimately shedding its outer layers to become a white dwarf. The exact timeline and details of these changes are still a subject of ongoing scientific research and investigation.