How long can the energy of a star produce for?

A star can produce energy for billions of years, depending on its mass. Smaller stars, like red dwarfs, can burn for tens to hundreds of billions of years, while larger stars have shorter lifespans, typically ranging from a few million to a few billion years. The fusion processes in a star's core convert hydrogen into helium, and once the hydrogen is depleted, the star will evolve into different stages, ultimately leading to its end.