"In front of the hall" is the front or hall of the principal room, which refers to the front of people and represents openness and seriousness; "Pillow" means "behind", representing privacy and respect.

The whole sentence means:

Teach children to be open and fair. The "front of the classroom" here contains two meanings: one is face-to-face education for children; One is to educate children in front of everyone. In ancient times, there were often many people in a family. "Before class" is a public place, and "teaching children before class" is generally a more formal and serious admonition for children when they make mistakes, including the meaning of apologizing to others for their children.

If there is anything wrong with your wife, don't talk about her in front of the children or others, but quietly correct her where no one is behind. This is respect for your wife.

This is an old saying, which comes from Zhu Xi's family instructions.

Zhu Xi's family precepts are also known as Zhu Bailu's family precepts, or family precepts for short.

The whole sentence is: "teach your son before class, teach your wife by the bed, suit the remedy to the case and tailor it to your own circumstances."