In how many years will the sun stop shining?

Depends on how you classify shining.

The Sun will stop being the small "yellow" object in the sky in about 4.5 billion years.

It will then turn into a red giant, a massive object that will almost touch Earth - not that anything will be alive to see it. That will last for about another billion years.

After that, it will shed it's outer layers in a planetary nebula, taking most of the surface of Earth with it.

All that is left, is a hot white dwarf, that will still have heat to radiate, and that will continue for billions of billions of years.

So, the Sun will still shine in billions of years time, but "not as we know it"