# list that may vary
errors_list = ['It has no letters', 'It has symbols', 'The last letter is a space']

for i in errors_list:
    print("     " + str(errors_list.index(i) + 1) + "- " + i + ".")

1- It has no letters.
2- It has symbols.
3- The last letter is a space.

1- It has no letters,
2- It has symbols,
3- The last letter is a space.

for i in errors_list[0:-1]:
    print("     " + str(errors_list.index(i) + 1) + "- " + i + ",")
print("     " + str(len(errors_list)) + "- " + errors_list[-1] + ".")

for i, err in enumerate(errors_list):
    print("     {}- {}{}".format(i+1, err, ';' if i+1 != len(errors_list) else '.'))