A Coronavirus (COVID-19) is a hole full of genetic material and few proteins (spikes). The genetic material is enveloped by the oily layer. On the surface of the oily layer, there are numbers of crown-shaped spikes that attach itself to the human receptor cells and hijack it.
Once inside the human body, the virus attacks two types of lung cells.
Goblet cells: The purpose of the cells is to secrete mucus in order to remove dirt and bacteria from (and so cleanse) the air entering the lungs.
Ciliated cells: The purpose of the cells is to filter out pathogens.
COVID-19 spikes have two components the receptor-binding domain (RBD), and a cleavage site. The RBD helps to attach the virus to the host cell and then it made entry into the cell by penetrating an outer wall of the host cell. The cleavage site acts as an opener that allows the virus to break the cell. The RBD receptor is evolved to target human AC2 receptor cells.
Once it enters the human cell it releases its genetic material (RNA payload). The virus then uses cell structure to make multiple copies and produces more viruses. The cell filled up with more and more viruses until it self-destroys and releases new copies of viruses to the neighboring cells. The new viruses then hijack neighboring cells and make more copies.