Kosovo (Southeast Europe) and Hawaii (Central Pacific, USA) are ~12,500 km (7,770 mi) apart—roughly 1/3 of Earth's circumference.
The original answer claimed distance "cannot be determined as they are not within the same geographical proximity." This is incorrect. Any two points on Earth have a calculable great-circle distance. The phrase likely meant "not practically relevant for travel planning" or "no direct transport link."
Kosovo's antipode is in the Pacific Ocean south of New Zealand. Hawaii's antipode is in Botswana. They are not antipodal—but they're about as far apart as two inhabited places can be.
So: ~12,500 km, 20+ hours travel, 11–12 hour time gap. A journey across the planet.