First we need to understand what Coronavirus actually is. Coronavirus is a family of viruses which causes the COVID-19 disease. The disease causes respiratory illness (like the flu) with symptoms such as a cough, fever, and in more severe cases, difficulty in breathing. The structure is almost 80–90% similar (genetically) to the virus which causes the Severe Acute Respiratory Syndrome. Hence this virus is also called as Sars-CoV-2.
The Sars-CoV-2 is a spiky virus which consists of a protein membrane (covering) outside and a strip of Ribonucleic Acid from inside. The spiky surface helps the virus to get stuck on to the receptors which are present on the inner lining of the human lungs which helps the virus to break into the cell.
This means that, the virus has now access to the machinery which helps manufacture cells and hijacks it to produce more copies of itself before breaking out of the cell again and killing it in the process.
Further Reading : Science Direct