Complex sentence: Antisana is a volcano of the northern Andes, in Ecuador, 5,753 m high; also a village on its flanks, 13,000 ft high, the highest village in the world.
Split into simpler sentences: Antisana is a volcano of the northern Andes, in Ecuador. On its flanks, at 4,000 m (13,000 ft), sits the highest village in the world.