[septimus111]

Not knowing anything about you, I'll assume that

- you are starting with the equivalent of a high school level of maths

- you want to take a ML course or read an ML book without feeling totally lost

As some commenters have said, Calculus, Probability and Linear Algebra will be very helpful.

Some people like to recommend the "best" or "most important" books which you "should" read, but there is a strong chance these will end up sitting on a bookshelf, barely touched. So I will recommend some books which are perhaps more accessible.

- Calculus by Gilbert Strang

- Linear Algebra by Gilbert Strang

For Probability: I don't have any favourites, sorry.