In Belgium (french speaking part of the country, like in France) we call the ground floor (where you enter the buidling) "rez-de-chaussée" (or "rez" for short)

In Belgium (french speaking part of the country, like in France) we call the ground floor (where you enter the buidling) "rez-de-chaussée" (or "rez" for short) which is the equivalent of 0 and then the first floor, numbered 1, is on top of it and you use an elevator or stairs to reach it.