It just means to take a pen and go over your original pencil lines in ink. I find it makes the lines a lot sharper, which really helps me out (<_>).If you're interested in trying out such a technique, I recommend using Sakura pens. They're kinda expensive, but for me, worth it.
But that's really cool that you know two languages! What was your first? I'm trying to learn Spanish myself, but to really get a language, one has to travel to a place where its spoken all the time...