From what I remember pre-calculus introduces you to stuff like limits, defines what it means for a function to be continuous, intermediate value theorem, and goes over a few helpful tricks for solving various types of funky functions. I didn't think it was hard but that really depends on the person and how comfortable they are with mathematics.

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If you want to take a look at what kind of material you're likely to cover I might look at the free online resource Khan Academy. (His specialty is in math but he does cover other areas of study)