It depends on what university and program you’re applying for. The most common prerequisites for medicine and dentistry are Year 12 subjects like Mathematics, Chemistry, English and Biology—but some courses don’t have any subject prerequisites at all. For Mathematics, different levels or subjects are required by different universities—full details about this can be found here.
(It’s also worth noting that while some courses have subjects that they recommend you take in high school, ‘recommendations’ are only optional, meaning you can still gain entry even if you haven’t done those subjects.)
For a full list of the high school subjects required for each course, please refer to this page.