What is Multi dimensional array in Data structures? 

Other people will give you much better answers (or provide more information). Have you looked at https://www.w3schools.com/php/php_arrays_multidimensional.asp (first link that came up, the language (PHP) does not matter to understand multi dimensional arrays)?

An array contains a collection of elements, such as integers, strings and booleans.

Let's say we have: Array = [1,2,3,4]

Then Array[0] = 1 and Array[2] = 3 

A multidimensional array contains arrays as its elements. 

MultiDimensionalArray = [ [1,2,3,4], [5,6,7,8], [9,10] ] (this array has 2 dimensions)

Then the first position of this MultiDimensionalArray will be MultiDimensionalArray[0] = [1,2,3,4]

if we want to access one of the numbers in this array, we would specify a second dimension: MultiDimensionalArray[0][1] = 2.

Does this help?

Other people will be able to help you further, but I highly recommend reading/searching about these things yourself first and explain the parts that you do not understand, that way people can help you more and you will learn faster.

Good luck!

14 minutes ago, Dagl1 said:

Other people will be able to help you further

You have said everything I was going to say

Well, one more thing. The "list of lists" or "array of arrays" description is one way of thinking about 2D arrays, and is how many programming languages work.

But you can also think of it as an explicit, 2D array:

A = [11, 12, 13, 14, 15, 16;
 
     21, 22, 23, 24, 25, 26;

     31, 32, 33, 34, 35, 36]

That is a 3x6 array. Some languages treat multidimensional arrays like this so you can references elements of the array as A[2,4] (which would equal 24 in this example).

And just a bit of terminology. A 1D array is often called a "vector" in mathematics. A 2D (or higher dimensional) array is called a "matrix".

In some programming languages, arrays of any number of dimensions are called "tensors".

Lists and arrays are very similar concepts. Some languages have either lists or arrays. Some have both, with slightly different properties. Typically, an array has a fixed size while a list can have things added to the end, or inserted in the middle.