What does it mean when asked to find lcm using prime factorization?

LCM means least common multiple, and while doing prime factorization. Prime factorization is basicly, every other whole number can be broken down into prime number factors. It is like the Prime Numbers are the basic building blocks of all numbers.

So you would do Prime factorization, and take the smallest multiple that leads up to the number you are doing the prim factorization on.

Hope that helped!

(Below is an example)