A low-mass star, like the sun, is a star that was created by the gravitational collapse of large molecular clouds. The collapse of these clouds causes the matter to be pulled through a disk-like center, which eventually forms into what is called a protostar.
Protostars are hard to see and study due to the amount of dust and gas surrounding them, so there is less known about them than other stars. These stars follow a similar pattern of life and death as other stars. Once they use up the fuel in their core, the core shrinks, which causes the atoms outside the core to shrink and speed up their fusion. This in turn makes the star brighter, but it also causes the star to grow its outer areas, turning it into a red giant.