Dio, a Roman consul and historian, said this in his history of Rome. he was talking about the rebellion of the Iceni Queen Boudica against the Romans in Britain. It was bad enough that the Romans nearly had to abandon their new province, but the fact that it was a women leading the fighting made it doubly bad. (For more about Boudica and her rebellion see Celt of the Month.)
In Rome a woman had few rights. No matter how wealthy she was, she was still considered the property of her father's family, even after marriage. She didn't have her own name. She was always given the feminine version of her father's name. So if her father was Julius, she'd automatically become Julia. If her Dad was Agrippus, she'd be Agrippina. She was not allowed to vote, hold office or serve in the military. If she divorced her husband, the father automatically kept the children. She could inherit property, however, keep her own money, ask for a divorce and write her own will.
The position of women in Celtic society was quite different. Celtic women were definitely allowed to hold office in their own right. Queen Cartimandua ruled the Brigantes. Queen Boudica ruled the Iceni after her husband Prasutagus died. He had actually left his kingdom to his two daughters. Women like Boudica led men into battle. In the Tain Bo Cuailnge, Cuchulain is taught to fight by the warrior maiden Skatha. He fights against the forces of Queen Maeve, who leads her army into battle. There are examples of Celtic women being diplomats, ambassadors and druids as well.
So the Celts were far more forward thinking regarding women's rights than some societies existing even today.