The Student in the story never does come to understand the reality of love. He believes his beloved will dance with him if he brings her a beautiful red rose. He searches for one, and then one morning, considers it a piece of good "luck" that he finds one growing outside of his window. It is so beautiful that he assumes it must have a long Latin name.
His beloved, however, is vain and shallow, and she rejects the rose because it does not match her dress, and rejects the would-be lover as not good enough for her. The lesson the Student, who is about as shallow as the girl, learns is as follows:
“What a silly thing Love is,” said the Student as he walked away. “It is not half as useful as Logic ..."
He goes back to his books.
The readers, however, learn a different lesson. We have seen how deeply the Nightingale believes in love, so much so that it is willing to sacrifice its life so that its blood can turn a rose red for the Student to give to his lover. We hear the Nightingale say:
Surely Love is a wonderful thing. It is more precious than emeralds, and dearer than fine opals. Pearls and pomegranates cannot buy it, nor is it set forth in the market-place.
The Nightingale tries to tell the student that love is more important than philosophy but he cannot understand the words.
Wilde's story is an example of dramatic irony, which is when the audience knows what characters in a tale do not. We understand and appreciate the sacrifice the Nightingale made, and come to understand the importance of love, but this lesson is lost on the Student.