“she.” This is the figure of speech personification. Nahum is a prophecy against Nineveh, who here is portrayed as a woman.
“stripped naked.” Although the meaning of the Hebrew is debated, “stripped” fits the context and the culture. It was common that when a city was captured, people would be lead away as captives stripped naked (Isa. 20:4). Egypt’s Queen Cleopatra committed suicide so she would not be paraded naked through the streets of Rome.