Complex sentence: Yazda had worked and still has been working to locate and help free the Yazidi women and girls who more than 3000 still held hostage by Islamic State and victims of human trafficking and sexual slavery.
Split into simpler sentences: Yazda had worked and still has been working to locate and help free the Yazidi women and girls who more than 3000 of whom are still held hostage by Islamic State. Those women and girls are victims of human trafficking and sexual slavery.