Theory:

    He was half hoping that the warrior would have forgotten the challenge, but these hopes were dashed when he saw his opponent sitting, stripped to the waist, on a rock on the other side of the pool. The warrior was rubbing oil on his body. He saw Ranji beneath the sal trees, and called a challenge across the waters of the pool.

    “Come over on this side and fight!” he shouted.

    But Ranji was not going to submit to any conditions laid down by his opponent.

    “Come this side and fight!” he shouted back with equal vigour.

    “Swim across and fight me here!” called the other. “Or perhaps you cannot swim the length of this pool?”
 
    But Ranji could have swum the length of the pool a dozen times without tiring, and here he would show the warrior his superiority. So, slipping out of his vest, he dived straight into the water, cutting through it like a knife, and surfaced with hardly a splash. The warrior’s mouth hung open in amazement.

    “You can dive!” he exclaimed.

    “It is easy,” said Ranji, treading water, waiting for a further challenge. “Can’t you dive?”

    “No,” said the other. “I jump straight in. But if you will tell me how, I will make a dive.”

    “It is easy,” said Ranji. “Stand on the rock, stretch your arms out and allow your head to displace your feet.”
Explanation:
 
Later the narrator stated that Ranji thought of going to the pool where the fight happened on the previous day. While he was going there, Ranji was in a semi-hope that the other boy would have failed to remember the challenge. The reason behind the statement was Ranji did not have enough strength to fight with the opponent. Unfortunately, all his hopes were shattered when he saw his enemy sitting on a rock on the opposite side of the pool. The Warrior had removed his dress till the waist and was rubbing oil on his body. It implies that the boy was getting ready for the fight by applying oil to his strong body. Then the boy saw Ranji standing underneath the sal trees and challenged him from right across the pool.
 
The Warrior then shouted from the other side of the pool and told Ranji to come over to his side and fight. On the other hand, Ranji wasn't going to surrender to the conditions that his enemy was laying down. It implies Ranji was unwilling to accept the strange boy's command. As a result, he responded with equal vigour and told him to come to his side instead. The other boy asked him to swim across and fight with him. He even humiliated Ranji by claiming that Ranji was not coming to the other side because he could not swim the entire length of the pool.
 
Ranji, on the other hand, was an expert swimmer. However, the Warrior was unaware of Ranji's swimming ability. The narrator then claimed that Ranji could swim the length of the pool several times without tiring. As a result, Ranji decided to demonstrate his superiority to the Warrior by swimming. Ranji removed his vest and dived right into the pool, cutting through it like a knife and came smoothly onto the surface. After seeing Ranji's performance, the Warrior's opened his mouth in surprise.
 
Later, the Warrior remarked that "You can dive!" After hearing the boy's statement, Ranji told him that it was quite simple to dive into the pool. Ranji asked the Warrior whether he knew how to dive into the pool. On the other hand, the Warrior said that all he knew was to jump directly into the water. The boy then asked Ranji if he could teach him how to dive in the pool. After hearing the boy's statement, Ranji assured him that learning to dive was simple. He told the Warrior to stand on the rock, stretch his arms out, and let his head move his feet.
 
Meanings of the difficult words:
 
S.No
Words
Meanings
1
ChallengeA call to someone to participate in a competitive situation or fight to decide who is superior in terms of ability or strength
2
StripTo remove clothing or covering from
3
VigourPhysical strength and good health
4
Displace Take over the place, position, or role of
5
AmazementA feeling of great surprise or wonder
Reference:
National Council of Educational Research and Training (2008). It so happened. The Fight- Ruskin Bond (pp. 45-54). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.