Would you describe this code ?

Question

Would you describe this code, specially line 3 (comprehensively) ?

https://code.sololearn.com/c4n45ypZOEDv/?ref=app

Answer 1

msg = "Numbers: {0} {1} {2}". format(nums[0], nums[1], nums[2])

{0}=nums [0], If it was like {2} it's value would be equal to nums [2]

Answer 2

{n} in format string indicate to format to replace this piece (curly brace and n) with the n-th parameter in format call (n start from zero)