Complex sentence: The "Bougainville" class was a type of colonial aviso or sloop of the French Navy of the 1930s that were designed to operate in remote locations of the French Empire.
Split into simpler sentences: The "Bougainville" class was a group of colonial avisos, or sloops, built for the French Navy during the 1930s. They were designed to operate in the remote locations of the French Empire.