Women are accustomed not to do any work while the Candles are Burning

• See Shulchan Aruch 570:1
• Custom from Ancient days (ben Ish Chai).
• Beis Yosef says (570) that this is the sign that it is forbidden to have benefit from the light.
• Women represent Malchus and the light of Chanukah is an expansion of Malchus, so they have a Yom Tov while the candles are burning.
• The lighting is the Mitzvah, and even though women are obligated in Ner Chanukah, they are not lighting. So they fulfill the Mitzvah by being dedicated totally to the candles during the half hour while they are burning. This is the greatest expression of Pirsumie Nissa, publicizing the miracle of Chanukah.