When the stars are plotted on the Hertzsprung-Russell diagram, most of them fall into the curve called the main sequence. The main sequence stars are 'average' because many stars fall into this category, and these stars burn hydrogen into helium in their core, and they are relatively young ( age of a few billion years) .
Our sun sits in the middle of the main sequence curve in the HR- diagram, which means the it is a yellow dwarf star with a surface temperature of about 6000 K, it has an average size, and it is hot enough for hydrogen fusion—in other words a typical star.
