It doesn’t directly, in most cases. I would guess, though, that your question indicates that you are unhappy about a general education math requirement at your school. Knowing something about math is part of being an educated person. It will help you to understand what you read, and to manage any money that you may make. Not every class you take in school is intended to relate directly to your job; that is what a trade school is for. A university is designed to produce an educated citizenry and workforce, which means that most people take courses which may not see immediate career payoffs.

Even a writer needs to remember that 1 plus 1 must always equal 2. Math is an exercise in logic, and a good book will be also. Writings without logic will invariably come across as disconnected or unrealistic.