Who can help me explain the sentence "On the eighteenth day of the autumnal equinox, a hundred herbs bear seeds"? thank you

On the eighteenth day of the autumnal equinox, one hundred kinds of herbs produced seeds. At the beginning of early autumn, the grass is growing, the grass is growing as far as the eye can see, and the lush greenery has always been involved in our sight. At the beginning of early autumn, the grass is growing, the grass is growing as far as the eye can see, and the lush greenery has always been involved in our sight. The vegetation in early autumn is ripened by solar terms in a short time, and it is no longer delicate, and the faint smell of grass is no longer. It becomes hard and solid, posing a mature posture.

Autumn is coming, and the weather is getting cooler and cooler. In the dense branches and leaves, the dense cicada singing in summer becomes sparse or even gone, lacking the thickness, appearance and overwhelming noise. Most cicadas have stopped singing, and only a few cicadas are still hissing high and low, trying to keep the old buzz going.