This is a list of lists, where each inner list represents a row in a matrix.

So, the first row of the matrix is [1, 2, 3], the second row is [4, 5, 6], and the third row is [7, 8, 9].

Overall, this matrix is a 3x3 matrix with the following elements:

1 2 3
4 5 6
7 8 9