An array is a basic data structure to store a collection of (usually similar type) elements sequentially. Imagine you have to add 10 numbers. You can easily declare 10 variables to store them and then add those variables together. But what if you have to add 100 numbers or even more. It's not very efficient to create 100s of variables to store numbers and use them. Thats where array comes in. Array is a variable that can store multiple values and can access those values using something called index.

Try to think of this as a really tall building, that has, lets say 50 floors. The name of the building is same (say XYZ plaza) but you need a floor number too (index in case of array) to go to particular apartment.

source: leetcode.com array and string tutorial

Now here's an example of array (building) A of 6 floors, starting from 0 (don't forget the ground floor ;) ). And if you want to access 8 you have to do this like it: A[2] that is building (variable) name and a floor (index) number. Really cool and simple right! :D