Dimensions can be seen as the total number of physical parameters that a particular object holds in space. For example- for a box, we have 3 parameters: its height, length, and breadth.
0-Dimension: An object is said to be 0-Dimensional if it has 0 physical parameters to measure. To understand it theoretically, think of a very small dot. We can’t define any of its physical parameters.
1-Dimension: An object is said to be 1-Dimensional if it has 1 physical parameter to measure. Now, let us take a 0-D dot that we defined earlier. Place ten of such dots in a line attached to each other. We will see a straight line, for which we can define the easiest physical parameter as its length.
2-Dimension: An object is said to be 2-Dimensional if it has 2 physical parameters to measure. Let us take a 1-D line that we defined earlier. Place ten of such lines side by side attached to each other. We will see a plane square area covered by those lines, for which we can define two physical parameters- length (made from dots) and breadth(made from lines).
3-Dimension: An object is said to be 3-Dimensional if it has 3 physical parameters to measure. Let us take a 2-D plane that we defined earlier. Place ten of such planes side on top of each other. We will see a box type volume made by those planes, for which we can define 3 physical parameters- length (made from dots), breadth(made from lines) and height(made from planes).