COVID-19 is spread like other common viruses which cause a cold or the flu. This is typically via small droplets that are spread when an infected person sneezes or coughs.
Being within close proximity to an infected person for a prolonged period of time (usually within 6 feet for 10 minutes) can increase the risk of infection.
Virus particles can also settle on surfaces such as doorknobs, countertops, and drinking glasses, or be transmitted through contact via shaking hands or kissing.
For more information see: CDC: Spread