int 3 b2;

This is a declaration of a two-dimensional array named b. The array b has 2 rows and each row contains a pointer to an integer.

However, this declaration is invalid because the syntax is incorrect. In C/C++, the declaration should be written as:

int *b[2][3];

This declares a two-dimensional array b with 2 rows and 3 columns. Each element of the array b is a pointer to an integer.