What is the length and breadth of a square meter?

The simplest answer would be 1 meter by 1 meter, but in truth, any combination of two lengths that are reciprocals of each other can also give you 1 square meter, for example:

0.5 m x 2 m = 1 m2

0.25 m x 4 m = 1 m2

0.4 m x 2.5 m = 1 m2

0.001 m x 1000 m = 1 m2

etc., etc. etc.