What is the meaning of "day length" in "Day length flies"

"The days are long" should mean that spring has come and the days are getting longer and longer. As the name implies, "flying catkins are light" means that flying willows bloom in accordance with the national "calendar". There are 24 o'clock in Hua Xinfeng, from the slight cold to Grain Rain, every five days is a flower letter, and each festival should have three seals and three incense; According to the three letters of the vernal equinox, they are begonia, pear and magnolia. Pear blossoms are backward, and Qingming is forward. The poet writes about the scenery of the age and is meticulous. In this season, the breath is fragrant and moist, the moss in Chi Pan is fresh and green, and the forest is buzzing. Spring has passed, it's getting late, and the expression is more subtle. Where should I put the Qingming Flower Letter? That's tung flower, wheat flower and willow flower. So the poet went on to write, "The days are long and the catkins are light." There is a poem in ancient times: "Begonia all fall, birds all fly, and the weather is getting longer and longer." We can watch it together. Literary critics must say here: write about scenery; Things! I don't know the timing, but it touches people's hearts.