Because Afghanistan is a land-locked country, the US-led NATO coalition in Afghanistan receives supplies that arrive in Pakistan‘s port in Karachi. The supplies then take a full week to travel overland by truck to reach Afghanistan. When Pakistan shut down this supply route in 2011, supplies had to take a very long route through Central Asia.
So now the NATO coalition forces are asking Pakistan to permit supplies to arrive in Pakistan‘s China-build Gwadar port. From there they would be loaded onto trucks and reach Afghanistan within 24 hours, rather than a week.