proper noun/ɛɡ.za.ɡɔn/
mainland of France
“Qu’est-ce que l’Hexagone ? C’est la France. Mais le mot «France», entaché d’une affectivité suspecte, petite-bourgeoise, tend à basculer vers le folklore ; le langage contemporain lui préfère celui d’Hexagone qui, dans sa pureté fonctionnelle, semble mieux adapté à la définition d’une grande nation moderne.” — What is the "Hexagon"? It is France. But the word "France", blemished by a suspect, petit bourgeois affectivity, tends to fall into folklore; the contemporary language prefers "Hexagon", which, in its functional purity, seems better adapted to the definition of a great modern nation.
From the shape of France; which roughly corresponds to a hexagon (hexagone in French).