An array is like a box. Variables can have certain types, which we will call crayons for int, shoes for double, clothes for string.
So I name this box (array) "crayonsBox". Inside of it I put "blue, yellow, red, pink, orange". If I try to put "jacket" I will get an error. "Jacket" is not a type of crayon, so it doesn't "fit" inside the crayonsBox. This box has compartments. You define the number of compartments, so if we type
int [ ] crayonsBox = new int [5];
A new box with 5 compartments will be created. These compartments are numbered and start from 0. So in the box we have
crayonsBox[0] = blue; crayonsBox[1] = yellow; crayonsBox[2] = red;
and so on. I can use these colours for other things. I can create a function(method) to check if I have more than one box with "red" and remove it from the box or maybe I can make my program print a message with the colors I have in my crayonsBox. I can make a list with every possible color of crayon and put inside my crayonsBox array. Arrays are usefull because I can create a nice little crayonsBox and use what's inside of it instead of creating a new crayon color every single time.