Complimentarianism is the theological position that there are different roles between men and women in the Christian church, church leadership, marriage, etc. Essentially it holds to a hierarchical structure between men and women. This position focuses on function and calling as revealed in the Bible and does not assert that women are inferior in nature.
This position would negate the possibility of women being pastors, elders, bishops, etc. Furthermore, it would assert that the husband is the head of the wife as well as the head of the family. See Egalitarianism which teaches complete equality and Egalitarianism and Complementarianism, what's the difference?