Hi Taylor and Laura,
An array is a rectangular arrangement so 12 apples might be arranged in a 4 by 3 array
(mathematicians always mention the number of rows first and then the number of columns)
or a 3 by 4 array
or a 2 by 6
or a number of other ways including a 1 by 12 and a 12 by 1 array. The only requirement is that there be the same number of apples in each row and the same number of apples in each column.
Arithmetically you are writing 12 as a times b and then putting the apples into a rows and b columns.