Because it is a French Department. Kind of like America owns places in other parts of the world.
French Guiana (Guyane Française) is an old french colony. So, that's why they speak French there.
no
78.6% of the people in French Guiana speak French...
French polynesia is part of France, it is a "collectivité d'outre-mer". The French Government takes care of the administration and French is the official language, even though the dalects are still...