To make a list to go to the market, people take a sheet of paper and start writing from top to bottom what you need to buy. This is the simplest way of making a list.
An array is a list of items. Adding more at the end is easy. And adding more space (including a second sheet of paper) is also possible.
It is not easy to add things in the middle of the list. It requires you to copy every item one line under each of them to have the free space where you want the new item.