It means: a gallop, smoke rolling, princess smiling. No one knows that fresh litchi has been sent from the south.
This poem chooses to send lychees to the imperial concubine Feitian, vividly revealing that the rulers, in order to satisfy their appetite, do not hesitate to mobilize the masses, wasting people and money, and effectively castigate the arrogance and extravagance of Tang Xuanzong and Yang Guifei.