France is divided in "régions". Until recently, there were 26 of them, and a 27th was added. So, 5 of them are DOM-TOM (Département d'Outre-Mer, Territoire d'Outre-Mer) , or overseas territories.
The capital of France is Paris, and its région is Ile-de-France.
My région is Picardie. You can easily find it on the map below, right above Ile-de-France, in green.
Each région is divided in "département", and there are 101 of them. Mayotte was added recently.
95 of these départements are in metropolitan France, and then there is Corsica. The others are in the DOM-TOM.
The départements are classified in alphabetical order, and each has a number according to their rank in the alphabet. The first département, for example, is "Ain".
I was born in the Aisne Département, which is 02. I grew up in the Oise département: 60.
These numbers are used in the zip codes and in license plates. So, you always know where a vehicle is coming from, and you can easily tell where a town is situated just by seeing its département number. Unless you've never learned your Geography lessons!