Theory:

     Mr. Fogg and Sir Francis Cromarty, after searching the village from end to end, came back without having found anything.
 
     ‘I shall go on foot,’ said Phileas Fogg.
 
     Passepartout, who had now rejoined his master, made an unhappy face, as he thought of his magnificent Indian shoes. Happily he too had been looking about him, and, after a moment’s hesitation, said, ‘Monsieur, I think I have found a means of conveyance.’
 
     ‘What?’
 
     ‘An elephant! An elephant that belongs to an Indian who lives but a hundred steps from here.’
 
     Kiouni—this was the name of the animal—could doubtless travel rapidly for a long time, and, in the absence of any other means of transport, Mr. Fogg resolved to hire him.
Explanation:
 
Mr. Fogg and Sir Francis had searched the whole village of Kholby; but, they weren't able to find any vehicle to travel to Allahabad.
 
Mr. Fogg and Francis.jpg
Mr. Fogg and Francis

Finally, Mr. Fogg decided to cross the fifty miles by walk. He informed the same to Sir Francis. Passepartout also rejoined them both. He was worried to overhear the conversation between Sir Francis and Phileas Fogg. He did not want his impressive shoes to get spoiled.

He then looked at his surroundings and became happy, and after a moment, hesitatingly revealed a suggestion. He claimed to have found some other means of transport to Allahabad. Both Mr. Francis and Mr. Fogg was surprised by Passepartout's answer. It was an elephant Passepartout had chosen as a vehicle. Passepartout explained that an Indian man who had the elephant in the Khloby did not reside so far, but a hundred steps from where they stood.

The name of the animal was Kiouni. He suggested an elephant ride from Kholby to Allahabad as it would surely help to reach Allahabad quickly. Mr. Fogg accepted the suggestion of Passepartout and decided to hire Kiouni for an hour to reach Allahabad.
 
Meaning of difficult words:
 
S.No
Words
Meaning
1.
Magnificent
Very impressive and beautiful
2.
Hesitation
A pause or feeling before saying or doing something
3.
Conveyance
The process of moving people, animal, goods etc. from one place to another
4.
Rapidly
Quickly
5.
Resolve
To find an acceptable solution to the problem or to make a determined decision
Reference:
State Council of Educational Research and Training (2019). Term-3 English Standard-7. A Journey by Train by Jules Verne (pp. 79-85). Published by the Tamil Nadu Textbook and Educational Services Corporation.