Explain the importance of filial piety to the chinese. how does the concept of filial piety relate to the confucian view of how society should function?

According to Confucianism, the society will function well if everyone knows their assigned place and does not question it. 

In a Confucian society, people are not equal, instead, there is a hierarchy:

ruler >subject,
father > son, (we can assume that  they mean parents> children)
husband > wife,
elder > younger,

friend = friend - here people are equal with respect to each other. 

So we see that filial piety is a way of ensuring that this relationship: father > son functions without a problem, and the Confucians believed that this is necessary for the proper function of the society.