There are many types of human coronaviruses, including some that commonly cause mild upper-respiratory tract illnesses.
The novel COronaVIrus Disease that first started in 2019 (a.k.a. COVID-19) is named after the crownlike spikes that protrude from its surface. COVID-19 is a new disease, caused be a novel (or new) coronavirus that has not previously been seen in humans.
The best way to prevent illness is to avoid being exposed to this virus.