It implies that in the Emperor Yao time the calendar was the solar calendar in which one year was divided into 20 solar terms.
3
帝尧听说舜非常孝顺,有处理政事的才干,把两个女儿娥皇和女英嫁给他;
Emperor Yao heard that Shun was a filial son with the talents of dealing with political affairs, and married off his two daughters, Ehuang and Nvying, to Shun.