Complex sentence: The Asiento allowed Britain a monopoly to supply 5,000 slaves a year to the Spanish colonies and the Navio de Permiso, a single yearly trading ship, the Annual Ship, carrying 1000 tones of imports to the yearly trade fair in Porto Bello.
Split into simpler sentences: The Asiento allowed Britain a monopoly to supply 5,000 slaves a year to the Spanish colonies. The Navio de Permiso permitted a single yearly trading ship, the Annual Ship, which could carry 1000 tons of imports to the yearly trade fair in Porto Bello.