There are at least two kinds of positive impacts that women's employment has for society. First, it helps a country economically. The average woman is as talented as the average man. This means that keeping women out of the work force deprives a country of their talents and keeps the country from growing its economy as well as it might. Second, it makes a society more equal and just in terms of women's rights. Keeping women from working prevents them from being socially equal to men.
You can argue that having women work hurts society, however. The main argument here tends to be that it breaks down traditional ways. It, for example, prevents women from staying home and taking care of their children. This, one can argue, leads to a break down in the traditional structure of the family and, thereby, harms society.