Great question — answering as the UphillTech team:
ML is broadly at the intersection of computer science and mathematics. Many mathematical topics are relevant, in particular linear algebra and probability, which are the main topics to understand to get going and be able to interpret algorithms and papers. Given ML touches on so many areas, I wouldn't try to learn them first, but follow an online course (from a reputable university/online source) and look further into maths as you need. (Putting your question through any decent LLM will point you in the right direction.)
Full answer by Carl: https://datascience.stackexchange.com/a/138092 (CC BY-SA 4.0).
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