Linux on old MacBook ?

Hello there. Not sure if it's the right sub not the right flair but here is my question : My mother would like to give Linux a try because MacOS are anoying a.d she doesnt like Windows, but she dont know anything about Linux (and I barely know the basics myself). However, she need to keep using her current Macbook for her work, at least until she knows how to handle a Linux Distro, and thus, would like to put Linux on her old Macbook (dual boot is not an option). It's a Macbook from 2008, with MacOs X (10.6) installed on it. Is there a way to put a begginer friendly Linux distro on this laptop, removing the curent OS, and if there is, how, what and what should we choose.