Hello! Very close and good question to ask.
It doesn't exactly remove space between all words, but suppresses the default behaviour of the comma in a
print, which is to put a space between subsequent arguments that are to be output.
Since the argument
': ' itself has a space in it, that space isn't removed, so the formatting matches what is wanted (plus, in this case, the instructions explicitly ask you to have that final argument, so that's another reason to put it in there)