What does the autumn wind mean?

There is no "autumn wind" in the 24 solar terms, only "autumn equinox".

"Autumnal Equinox" refers to the fact that autumn has already passed half since beginning of autumn, that is, the autumn is divided into two halves, and this day is the dividing point of the two halves. The season with the same meaning also has the vernal equinox.

The days between summer and winter are called "summer solstice" and "winter solstice".

There is also a solar term that is difficult to understand among the 24 solar terms, which means "curing summer heat". From then on, the hot weather began to hide, that is, it began to be less hot.