What are the second generation stars?
First generation stars were the originally formed ones after the Big Bang. Stars formed from matter remaining after the disintegration of first generation stars are classifies as second generation stars.
What are the characteristics of second generation stars?
A first generation star will only contain the elements up to iron. When the star disintegrates after becoming a supernova, the debris will contain the heavier elements. The debris may again coalesce to form another star which would be called a second generation star.
Is the Sun a second generation star?
The matter in the Sun and planets contains elements heavier than iron and hence the sun can be said to be a second generation star. The matter in the Solar System (including the matter in our bodies) was once part of a supernova.