This book is an introduction to the language and standard proof methods of mathematics. It is a bridge from the computational courses (such as calculus or differential equations) that students typically encounter in their first year of college to a more abstract outlook. It lays a foundation for more theoretical courses such as topology, analysis and abstract algebra.
Knowing that the Curry-Howard correspondence exists is important if you care about the CS magic that makes lean work and to understand how term mode and tactic mode relate to each other but again it’s really not necessary to understand the correspondence itself to use lean as a proof assistant. (And this is covered extensively in “Theorem proving in Lean” if that’s your jam).
Whatever mathematical background you have is obviously helpful and will widen the scope of what you can do, but you don’t need to learn a huge amount of foundational mathematics to get your hands dirty in lean. For example, “The Mechanics of Proof” by Heather Macbeth was written as a course for 1st year undergrads so only assumes high school maths knowledge. Here’s a list of learning resources that the lean prover community recommends https://leanprover-community.github.io/learn.html
One thing I would add is if you want to learn about proof writing in general there are a lot of good resources out there including “The Book of Proof” which is free online. https://rcsnyder.github.io/open-frontier-curriculum/07-resou...
I personally really enjoyed Jay Cummings’ “Proof: A long-form mathematics textbook” which is on that list as it provides lovely little intros to various areas of mathematics along the way. I have done every exercise in that book and had a lot of fun in the process.
But these aren’t things you necessarily need to do before getting started in lean.
[0] Book of Proof by Richard Hammack https://www.people.vcu.edu/~rhammack/BookOfProof/
[1] Linear Algebra: Step by Step by Kuldeep Singh https://www.google.com/books/edition/Linear_Algebra/BJNoAgAA...
[2] Number Theory: Step by Step by Kuldeep Singh https://www.google.com/books/edition/Number_Theory/YZr9DwAAQ...
[3] Undergraduate Analysis: A Working Textbook by Aisling McCluskey and Brian McMaster
https://books.google.com/books?id=7U9HtAEACAAJ&printsec=copy...
There's even more relevant book for you[4]
[4] Foundations of Applied Mathematics by Jeffrey Humpherys, Tyler J. Jarvis, Emily J. Evans
https://books.google.com/books?id=CEc3DwAAQBAJ&pg=PR3&source...
We used this in my Discrete Mathematics class (MATH 2001 @ CU Boulder) (it is a pre-requisite for most math classes). The section about truth tables did overlap a bit with my philosophy class (PHIL 1440 Critical Thinking)
Book of Proof has a free PDF version. It covers the basic styles of proof (necessary to learn but still not super advanced).
Other texts of this sort include Jay Cummings long form texts (I myself haven't worked through or even exaimed these but they seem popular.
