Complex sentence: Rio de Janeiro will host the 2016 Summer Olympics and the 2016 Summer Paralympics--the first time a South American and Portuguese-speaking nation will host these events, and the third time the Olympics will be held in a Southern Hemisphere city.
Split into simpler sentences: Rio de Janeiro will host the 2016 Summer Olympics and the 2016 Summer Paralympics. It will be the third time the Olympics will be held in a Southern Hemisphere city.