A people who make a woman their leader will never succeed

Women should not be appointed to positions of leadership or judicial authority over people, or to similar public offices. However, in private matters—such as overseeing a Waqf (endowment), managing the affairs of orphans, or administering a school—there is no harm in that.
Highlighting the limited capacity and natural weakness of women, and that they are not to share with men in public positions of authority, as appointing them to such roles is a cause of lack of success.
Allah created woman with a nature different from that of man. Some matters are not suitable for a woman to undertake due to her particular nature, just as there are matters that are not suitable for a man to undertake due to his own distinct nature.
The "negated success" here refers to success in the sense used in Shariah—attaining the good of both this world and the Hereafter. The prosperity of a nation's worldly affairs does not necessarily mean that it enjoys Allah's approval, for whoever is not obedient to Allah is not truly successful, even if outwardly he appears to be in the best of worldly conditions.
This Hadīth does not belittle women; rather, it provides proper guidance that directs their abilities in a manner suitable to their nature and strengths.