Multidimensional array initialization in C

Multidimensional array initialization in C

I am reading the book, "Programming in C" by Kochen and I am confused
where he explains the initialization of multidimensional array here. In
particular, I don't understand the meaning of the following sentence Note
that, in this case, the inner pairs of braces are required to force the
correct initialization. Without them, the first two rows and the first two
elements of the 3rd row would have been initialized instead. I'm not sure
what the heck the sentence means.