What does effacement mean?

Kaylan • ♡12/20/18 👼 & 3/12/20 🌈♡

Hey guys! I'm a FTM and I have a question that is probably going to sound really stupid, but I just want answers.

I got my first dilation check today. I'm a little over 1 CM dilated (yay! A little progress lol) and 70% effaced. I know I can stay at this point for weeks, however.

My question is, what happens when you get 100% effaced? Is that when your water breaks?