It means that Sima Guang broke the jar with a stone, and the water flowed out, so that the child could live.
This sentence comes from the History of Song Dynasty compiled by Tuotuo and Arutu in Yuan Dynasty. The original text: Sima Guang is a gentleman, and he is also from Xia County, Shaanxi Province. At the age of seven, Guangsheng was as awe-inspiring as an adult. When he heard about Zuo's Spring and Autumn Annals, he loved it and retired for his family, that is, he lost his big finger. Naturally, I can't put the book down, so I don't know whether I am hungry or thirsty. A group of children play in the court, one climbs the urn, and the foot falls into the water, and everyone abandons it. Just hit the urn with a stone and break it, and the water bursts, and the child will live.
Translation: Sima Guang is Jun Shi, a native of Xia County, Shaanxi Province. When Sima Guang was 7 years old, he was like an adult (in ancient times, an adult meant a weak crown, 16 years old, not 18 years old now). He especially liked to listen to Zuo's Spring and Autumn Annals, and came back to tell his family after understanding its main idea. From then on, I couldn't put it down for Zuo's Spring and Autumn Annals, even forgetting hunger, thirst and cold.
A group of children were playing in the courtyard. One child stood on the vat, fell into the vat and was flooded. All the other children ran away. Sima Guang broke the vat with a stone, and the water flowed out, so the children survived.
Extended information
Sima Guang is an outstanding thinker and educator, who is filial to his parents, loves his brothers, loyal to the king, wins the trust of others, and is respectful, thrifty, upright, gentle, humble and upright. In history, Sima Guang was once regarded as one of the three saints of Confucianism (the other two were Confucius and Mencius). Everything he does has statutes, and every word and deed is in line with etiquette. When he was in Luoyang, every time he went to Xiaxian to visit the grave, he must pass through the home of his brother Sima Dan.
Sima Dan is nearly eighty years old, and Sima Guang still serves him like strict father and protects him like a baby. Growing up, he never said anything casually. He said, "I have nothing better than others, but what I have done all my life has never been hidden."
His sincerity comes from his nature. People all over the world respect and trust him. People in Shaanxi and Luoyang all follow his example, compare with him and learn from his good character. If people do something bad, they say, "Doesn't Sima Jun really know?"