This is a common request when you are applying for admission to an institution. When a school, club, or similar organization asks a questions like this, their main purpose is to get to know you better. They most likely want to know whether you would be a good fit in their community. This is a sample of an answer to such a question:
"The reason why I am applying to HKU is because I believe this institution would allow me to explore both my academic and my extracurricular passions. I would like to study history at HKU because I believe the study of history is essential in our political and social world. We need to learn about the past in order to better face the challenges of the future. Moreover, I would also like to attend HKU because of its extracurricular activities. I am fond of dancing, and this activity has always been a big part of my life. I look forward to attending HKU and developing this talent as part of their award-winning dancing club.
In terms of my experiences, I have been part of the dancing club at my school for four years. In this time, we have organized many events, such as charity balls and exhibitions. Moreover, I have been part of the organization Me to We, where I have been volunteering for the past year. I would eventually like to reconcile my two passions: ballet and history, and use them to make a significant change in the world. I hope you will consider me for admission."