Based on your question, I'm assuming that you were given a choice on what to read, and you've chosen Kim by Rudyard Kipling. Therefore, your answer should be personal, and you need to consider specifically why you've chosen to read this book.
Kipling's Kim is an adventure/coming-of-age novel about an Irish orphan growing up in British-occupied India in the 1880s and 1890s. The story centers around the boy's adventures as he meets people from many different backgrounds and religions, from Buddhist lamas to undercover agents during a conflict between the Russians and the British. So, now you need to ask yourself what about this story makes you interested in reading it. Consider these questions to get started:
Do you like stories with adventure and suspense?
Do you like to learn about different cultures, languages, and religions and how they interact (i.e., Buddhism, Islam, Hinduism, Christianity)?
Do you want to learn about the history and geography of India?
Do you like stories in which the main character is a young person like yourself who has to go on a secret quest?
Do you want to know what it's like to be an orphan in an unknown place?
Good luck, and I hope you enjoy answering a question that is really about your own interests and connections to this book!