Theory:

     “My own garden is my own garden,” said the Giant; “anyone can understand that, and I will allow nobody to play in it but myself.” So he built a high wall all round it, and put up a notice-board: TRESPASSERS WILL BE PROSECUTED
 
     He was a very selfish Giant.
 
     The poor children had now nowhere to play. They tried to play on the road, but the road was very dusty and full of hard stones, and they did not like it. They used to wander round the high walls when their lessons were over, and talk about the beautiful garden inside. “How happy we were there!” they said to each other.
Explanation:
 
The giant insisted that it was his garden. He claimed to permit no one to play in his garden as it belonged to him. He wanted to have the garden only for himself, and so, he had chased children out of the garden. This harsh attitude reflects his lack of gentleness, courtesy and humanity. Then he constructed a high wall around his garden to avoid people entering it, especially children. He believed that the wall would prevent people from entering his garden without his notice. He also put up a noticeboard: TRESPASSERS WILL BE PROSECUTED.
  
The Selfish giant.jpg
The Selfish giant

The giant was merciless and selfish as he did not even let children play in his garden. The giant's ruthless activity affected kids. Children were upset as they had nowhere to play.

The children were no longer able to play, and they had nowhere to go. They tried playing on the road, but it was muddy and full of sharp stones, which they disliked. They used to talk about the lovely garden, and since they had no other option to play, they wandered around the garden's high wall after their classes were over. All they did was recall the days they had spent playing inside the giant's garden and exclaim, "How glad we were there!".
 
Children's recall.jpg
Children's recall on happy days spent inside the garden
 
Though they wanted to play there, they couldn't do so as, firstly, they were terrified of the giant; secondly, the huge wall around the garden had prevented them from entering the garden even during the giant's absence.
 
Meaning of difficult words:
 
S.No
Words
Meaning
1.
Permit To allow
2.
Terrified Very scared
3.
Ruthless Cruel and determined what you want without caring about others
4.
TrespassersA person who goes to somebody's land without permission
5.
ProsecuteTo officially charge somebody with a crime in court
Reference:
National Council of Educational Research and Training (2008). The Selfish Giant – Oscar Wilde (pp. 17-24). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.