Philosophy is about as broad a subject as you can find in a university curriculum. It addresses a wide variety of questions, some quite familiar (Does God exist? Why should I be moral? What does it take to make a just society? How is the mind related to the body?), others less so (What is time? What is space? Is it rational to rely on past experience as a guide to the future? If so, why, and under what circumstances?). Philosophers also raise questions about the methods and assumptions of the other disciplines. (What role do values play in scientific theories? What assumptions lie behind the conception of "health" that guides most medical practice?)
Because philosophy covers such a wide range of subjects, philosophers are affiliated with a wide range of intellectual inquiries. Some philosophers work on issues in linguistics. Others address questions in mathematics, political theory, theology, law, or cognitive science. This means that students with an interest in philosophy can also pursue their more particular interests. With this in mind, the department offers many courses without prerequisites; and many of these courses focus on particular subjects (e.g. bioethics, law, religion).
What all these philosophers have in common is a commitment to subjecting the views they consider to rigorous critical examination. The only way to know what it is like to engage in this sort of inquiry is to give it a try.