Theory:

HIGH above the city, on a tall column, stood the statue of the Happy Prince. He was gilded all over with thin leaves of fine gold, for eyes he had two bright sapphires, and a large red ruby glowed on his sword hilt.

One night there flew over the city a little swallow. His friends had gone away to Egypt six weeks before, but he had stayed behind; then he decided to go to Egypt too.

All day long he flew, and at night time he arrived at the city. “Where shall I put up?” he said. “I hope the town has made preparations.”
Explanation:
  
The story “The Happy Prince” is an exciting children’s folktale written by Oscar Wilde. The story opens with the narrator describing a beautiful statue. The statue was known as “Happy Prince” because he always remained cheerful when he was alive. After his death, his subjects erected a beautiful statue on a high platform overlooking the city. The statue was placed there in the memory of the Happy Prince. The statue was also covered with tiny layers of gold, and instead of eyeballs, two beautiful, gleaming sapphire stones were used. A gorgeous ruby stone was also embedded in the handle of his sword.
 
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Sword

The narrator then introduced another character to his readers: swallow (a tiny bird). He said that one night a swallow flew over the city. The bird was alone because all of his friends had gone to Egypt six weeks before. Although the swallow is not a human being, the narrator addresses it as “he” and “his”. The swallow did not go with his friends because he fell in love with a lovely river Reed (a tall, slender-leaved plant of the grass family that lives in water or on marshy terrain). When his friends found out about his interest in river Reed, they advised him to quit his relationship with Reed and accompany them to Egypt. Their warning was based on the fact that the Reed would disappear once autumn arrived.
 
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A swallow flying over the city
 
However, the swallow did not listen to his friends. Unfortunately, what his friends said had happened. After being rejected by the “Reed,” he considered leaving the city and returning to Egypt. Later, the swallow started flying to Egypt. At night, he reached the city of the Happy Prince, and he wanted to stay somewhere in the city. The bird said that hopefully, the town had made some arrangements for him to stay. The statement is humorous because the swallow believed he would get a better place in the big city.
 
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River reed
 
Meanings of the difficult words:
 
S.No
Words
Meanings
1 
Gild Covered thinly with gold leaf or gold paint
2
SapphireA precious stone, usually bright blue that is often used in jewellery
3
Ruby  A transparent, dark red precious stone, often used in jewellery
4
Glow  Have an intense colour and a slight shine 
5
Sword  A weapon with a long, sharp metal blade and a handle, used mainly in the past
6
Hilt The handle of a weapon or tool, especially a sword, dagger, or knife 
Reference:
National Council of Educational Research and Training (2006). Moments. The Happy Prince – Oscar Wilde (pp. 28-35). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.