Theory:

At that moment a curious crack sounded inside the statue, as if something had broken. The fact is that the leaden heart had snapped right in two. It certainly was a dreadfully hard frost.

Early the next morning the Mayor was walking in the square below in company with the Town Councillors. As they passed the column he looked up at the statue. “Dear me! How shabby the Happy Prince looks!” he said.

“How shabby, indeed!” cried the Town Councillors, who always agreed with the Mayor and they went up to look at it.

“The ruby has fallen out of his sword, his eyes are gone, and he is golden no longer,” said the Mayor. “In fact, he is little better than a beggar!”

“Little better than a beggar,” said the Town Councillors.

“And here is actually a dead bird at his feet!” continued the Mayor. “We must really issue a proclamation that birds are not to be allowed to die here.” And the Town Clerk made a note of the suggestion.

So they pulled down the statue of the Happy Prince. “As he is no longer beautiful he is no longer useful,” said the Art Professor at the University.

Then they melted the statue in a furnace. “What a strange thing!” said the overseer of the workmen at the foundry. “This broken lead heart will not melt in the furnace. We must throw it away.” So they threw it on a dust heap where the dead swallow was also lying.
 
“Bring me the two most precious things in the city,” said God to one of His Angels; and the Angel brought Him the leaden heart and the dead bird. “You have rightly chosen,” said God, “for in my garden of Paradise this little bird shall sing for ever more and in my city of gold the Happy Prince shall praise me.”
Explanation:
 
When the swallow died at the Prince's feet, an unusual sound came out from the big statue. It was the sound of the breaking of the statue's heart made of lead. It is said that the heart was so frigid that it split in two. Also, the reason for the cracking of the statue was because of the heavy frost.
 
The following day, the Mayor of the city and his councillors were taking a round of the area where the statue of Happy Prince was erected, and when he crossed the statue and looked up at it, he said that the statue of Happy Prince seemed untidy. The councillors generally agreed with whatever the Mayor said, so they asserted that the statue looked untidy. After looking at the statue, the Mayor said that the ruby placed in the sword's handle was missing, the sapphires from the statue's eyes were also missing, and the layer of the gold from its body was also missing.
 
The Mayor said that it seemed like it was a beggar statue, and the town councillors agreed with him. The Mayor found that a dead bird was lying near the feet of the statue. Then he told the town councillors to pass an order that birds were not allowed to die at the statue's feet, and the town clerk noted the suggestion given by him. The Art Professor of the University said that the Happy Prince's statue did not look beautiful and was not valid anymore, so they should demolish it. So they decided to melt it. At last, they melted the statue, which was made of lead, in a furnace. The supervisor of the foundry noticed a strange thing.
 
The heart of the Happy Prince's statue, broken into two pieces, was not melting in the furnace. So, they threw it in the dust heap. Coincidentally, people threw the heart of the Happy Prince where the dead bird was already lying. Later, in heaven, God asked one of his Angels to bring him the two most precious things in the city. Then the Angel brought the heart of the statue and the dead swallow bird. After seeing the heart of the two, God said that the Angel had brought the right thing. The Angel had chosen the right things, which were indeed the most precious things of the city. At last, God said that the bird would always sing in his Paradise garden, and the Happy Prince would stay in his city of gold and admire him.
 
Meanings of the difficult words:
 
S.No
Words
Meanings
1
Crack A line on the surface of something along which it has split without breaking apart
2
Dreadful Causing or involving great suffering, fear, or unhappiness; extremely bad or serious
3
ShabbyIn poor condition through long use or lack of care
4
Heap An untidy collection of objects placed haphazardly on top of each other
5
FurnaceAn enclosed structure in which material can be heated to very high temperatures, for smelting metals
6
BeggarA poor person who lives by asking others for money or food
7
MayorA person who is elected or chosen to lead the group who governs a town or city
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.