Basically saying keep checking ser until you find a '0', do not progress with the script until Arduino has finished it's function.
I understood your intent, and was pointing out that this code does not do quite that because it has a bug. It only checks every other character, and throws away the other half without looking at them:
while ser.read() == '0': // if the next serial input char is not '0'
ser.read() // read and discard the following char
[code]
-br
[/code]