The phrase "diverse nationalities" means that there is a wide variety of different countries or cultures represented in a particular group or population. Full definition
Their clients increasingly include multinational corporations and foreign governments who carry out commercial transactions, invest in public infrastructure, and exploit natural resources often in collaboration with other corporations and governments of diverse nationalities around the globe. (law.duke.edu)
Principal investigators (PIs) lead labs with members from diverse nationalities and cultures. (sciencemag.org)
Dublin is Ireland's capital city (Belfast and Cork are the island's other two major cities) and since its beginning around 988AD it has accommodated many diverse nationalities from the Vikings to the English invaders to the sailors, traders and writers who settled and lived here over the centuries... San Francisco City Breaks Shopping in San Francisco just got better with the opening of a new Bloomingdale's. (latebreaks.com)