The Sun has been shining for about 4.6 billion years. It’s expected to keep going, more or less the way it does today, for about another 5 billion. Stars in the Sun’s category - modest yellow ones - live about 10 billion years total. We’re halfway through.
When the Sun starts running out of hydrogen in its core, it will swell up into what astronomers call a “red giant.” It’ll get so big that it will swallow Mercury and Venus completely, and probably reach Earth too. (Long before that, though, the slowly brightening Sun will have made Earth too hot for liquid water - life as we know it won’t survive past about a billion years from now.)
After the red-giant phase, the Sun will shed its outer layers in a beautiful nebula and shrink down to a small, super-dense ember called a “white dwarf.” It’ll slowly cool for trillions of years, eventually fading to a dark cinder. That’s the future of our star - but on cosmic timescales we’re still in the long, calm middle.
