It means, in this case, "the political parties have as a goal that every second candidate chosen by the party should be a woman." It's another way of saying "Fifty percent of the candidates should be women."Hi
(Do quotas work? Some best cases:
Sweden. Most political parties practice ‘every second a woman’, that is 50% voluntary party quotas for candidate lists. 47.3 % women in parl. No 2 in the world.
What does the red part mean?