What does it mean to "travel back and follow it, just like swimming in the water"?

Translation

Going down the river to look for her, she seems to be in the middle of the water

Original poem

Jianjia

"The Book of Songs" (Pre-Qin Dynasty)

The jianjia is green and the white dew is like frost. The so-called beauty is on the water side. If you follow it back, the road will be long and blocked. Traveling back from it, Wan is in the middle of the water. The jianjia is luxuriant, and the white dew is still shining. The so-called beauty is on the water. If you follow it back, the road will be blocked and you will be able to advance. If you go back and swim from it, you will feel like you are swimming in the water. The jianjia is collected, and the white dew has not stopped. The so-called beauty is in the river of water. Go back from the road, resistance and right. If you go back and swim from it, you will be swimming in the water.

Introduction to "The Book of Songs"

The "Book of Songs" is the beginning of ancient Chinese poetry and the earliest collection of poetry. It collects poetry from the early Western Zhou Dynasty to the middle of the Spring and Autumn Period (11th century BC to 6 BC century), there are a total of 311 poems, 6 of which are Sheng poems, that is, they only have titles and no content, and are called the six Sheng poems (Nanmei, Baihua, Huashui, Youkang, Chongwu, and Youyi) , reflecting the social outlook of about five hundred years from the beginning of the Zhou Dynasty to the late Zhou Dynasty.