Cant get what is the use of last line inside print()...plz can anone explain

Question

for char in "abcdefghijklmnopqrstuvwxyz":
perc = 100 * count_char(text, char) / len(text)
print("{0} - {1}%".format(char, round(perc, 2)))

Answer 1

Thanks a lot

Answer 2

Okk but what for {0}-{1}% is being used here??