An array type is zero or more variables of a certain type.
An array has a length. This is the number of elements in the array.
The length of an array is gotten using the array length operator, which is documented as a structural operator.
Some languages have limits on the lengths of arrays, if your program has arrays larger than the maximum allowed by a language, your program will not run in that language.
Arrays can only be single-dimensional. The only way to get multi-dimensional arrays is to have an array of data-structures where the data structure contains another array.
The array access operator is documented as a structural operator.