Can someone help me understand this python 3 code? I have to create an empty matrix, but do not understand how

Matrix = [[0 for I in range(n)] for j in range(n)]

Also what are they adding 1 to at the bottom

import math import cmath #https://docs.python.org/2/library/cmath.html def cool matrix(n): wer Matrix = [ [O for i in range (n)] for j in range (n)] i=0 while (i