Should I talk about my hobbies in my personal statement for university? How do I make it relevant to the subject?

You should definitely include your hobbies, such as extracurricular activities you do at school or outside of school. Include the activities which you can use to demonstrate important skills you may have or may have gained from these activities, or important character/personality traits that they demonstrate. It is good to show your strengths and abilities which are not simply academic, and explain how you can utilise these at university, and specifically on your chosen course. Here is a section from my personal statement I wrote when applying for my Psychology degree where I discuss relevant extracurricular activities: "Outside of my curricular activities and studies, I have contributed to the wider community, having volunteered at GIFT charity, Jewish Care, and at my local synagogue as a teaching assistant for young children. Working with children had allowed me to display patience and specific communication skills."