Among them, "Lan" refers to the ship, which may refer to the author himself, and "Zhu Yan" refers to a beauty, a woman, which may refer to the person the author loves. The whole sentence means that the author and the person he loves are inseparable, but there are some doubts and bitterness between them, and it is hard to say goodbye in my heart.
This sentence expresses the complex feelings of ancient literati in the face of emotional problems, including sadness of parting, nostalgia for feelings and pain that is hard to give up. This kind of emotional theme is very common in China's ancient poems, and it is also one of the important ways to express the theme of love and parting.