What does it mean to wake up in spring and sing the return of Yan?

Spring has come. The weather in winter and summer is different in northern and southern China. Swallows fly to the south for winter in autumn and come back in spring. The word "Yan's Return" comes from Yan Shu's Huanxisha. The original poem is: a new word, a glass of wine. Last year, the weather got old. When does the sun set? There is nothing to do, flowers bloom and fall, and it seems familiar that Yan returns.