The first part of this sentence is "father and son, husband and wife from." Brothers are friends, and brothers are respectful. Young, friends, friends. You are loyal to your subjects. These ten meanings are shared by all. " It means: father's kindness, son's filial piety, husband's harmony, wife's obedience, brother's friend, brother's respect, friend's trust, friend's righteousness, monarch's respect and minister's loyalty, which everyone should abide by and not violate.
I think the word "teacher" in "being a teacher" here means: following, observing and following; "Xu" means: it is a general term and an "order", which means the above ten ethical orders: father's kindness, son's filial piety, husband's harmony, wife's obedience, brother's friendship, brother's respect, friend's trust, friend's righteousness, monarch's respect and minister's loyalty.