Creating a physical distance between yourself and others is one of the easiest ways to help prevent the spread of the virus.
Although a lot is still unknown about how exactly the virus spreads, recent research has demonstrated that spacing out helps minimise risk. In fact, the more distance the better. 1.5m has been recognised in Australia as a baseline because it is reasonably practical for people to achieve and lines up with other research about other viruses.
This is because the virus is carried in what’s known as respiratory droplets, which enter the air after someone coughs, sneezes or talks. The virus is then spread to others who are in close proximity to the infected person.
Essentially, the closer you are physically to someone with COVID-19, the more likely you are to also become sick. This is also why hugs and handshakes should be avoided at the moment, and masks should be worn when you are unable to physically unable to stand less than 1.5m from others.