I've asked Writeacher or Bobpursley to respond to your previous question. They know a lot more about poetry than I do.
However -- I think I understand this question.
To me, this quote means that poetry is the art of the impossible and of dreams. Obviously, a sea animal can't live long on land and can't fly. But these feats are possible in dreams and poetry. Poetry can vividly explain dreams and hopes.
Mohammed: Think on a very beautiful woman, vibrant, rich, exciting, full of life, walking beauty.
You see her. You fall in love with her. You want to speak to her, to tell her of your feelings. But she is unknown to you, and you cannot comprehend what it would be like to be with her for life. And, for you, she is untouchable.
Poetry is the means you seek to explain your feelings, it is the medium that allows you to reach out. And, you can use it to explain other emotions.
Use the examples below to explain "Poetry is the journal of a sea animal living on land, wanting to fly the air. "
thanks very much ms. sue and bobpursley :)
You're very welcome, Mohammad.