It involves people reducing the amount of close contact they have with each other in order to curtail the infection. We know that COVID-19 is a highly contagious virus which is spread through droplets in the air that are released when a person coughs or sneezes. So, maintaining a certain distance from other people while you're in public - far enough to stop you breathing in the droplets another person coughs or sneezes into the air - reduces your chances of catching the virus.