Theory:

Then he saw the statue on the tall column.
 
“I will put up there,” he cried. “It is a fine position with plenty of fresh air.” So he alighted just between the feet of the Happy Prince.

“I have a golden bed-room,” he said softly to himself as he looked round, and he prepared to go to sleep; but just as he was putting his head under his wing a large drop of water fell on him. “What a curious thing!” he cried. “There is not a single cloud in the sky, the stars are quite clear and bright, and yet it is raining.”

Then another drop fell.

“What is the use of a statue if it cannot keep the rain off ?” he said. “I must look for a good chimney pot,” and he determined to fly away.
Explanation:
 
While thinking about where to sleep, the swallow saw the huge statue of the Happy Prince standing on the high platform. Then he thought that it was a good place for spending the night. The place was covered with plenty of fresh air. So, the bird came near the feet of the statue of the Happy Prince. When he sat between the happy prince's feet and glanced about, he noticed that he was surrounded by gold. It denotes that the statue is gold-plated. Later he said to himself that he had a bedroom made of gold. He tucked his head under his wing as he was about to fall asleep. At that moment, a huge drop of water fell on his body.
 
Cattleya2017 Shutterstock (1).jpg
A statue was erected on a high platform
 
While seeing the drop of water fell on his body, the swallow said, "What a curious thing!" He made the statement since there were no clouds in the sky. Also, the stars in the sky appeared bright and clear. Generally, while raining, the sky would be covered with dark clouds, and as well it was impossible to see the stars in the sky. While the bird was thinking about the first raindrop, another drop fell on him.
 
Later, the bird said that if the statue couldn't stop the rain from falling, what was the use of it. It means that the bird considered resting between the statue's feet to keep him warm and help him survive the cold. Even though the swallow remained beneath the statue, two droplets fell on him. It made him think that the statue was useless because it couldn't keep the rain off. As a result, he believed he would be unable to sleep beneath the statue. So he thought that it would be best if he found shelter in a chimney pot. Then he decided to fly away from the place.
 
shutterstock_1626559642.jpg
Chimney pot
 
Meanings of the difficult words:
 
S.No
Words
Meanings
1
Statue A carved or cast figure of a person or animal, especially one that is life-size or larger
2
AlightTo land on something
3
Plenty A large or sufficient amount or quantity; more than enough
4
Cloud A grey or white mass in the sky made up of tiny floating drops of water
5
Drop A small round-shaped amount of liquid
6
Chimney A hollow structure that allows the smoke from a fire inside a building to escape to the air outside
7
Determined Having made a firm decision and being resolved not to change it
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.