"Virtus" originally meant "manliness," "strength," or "excellence". It encompassed the qualities considered desirable in a man, including physical courage, strength, and moral uprightness.
Over time, the meaning of "virtue" evolved to encompass moral excellence and good character in general, not just limited to men. It became associated with qualities like honesty, compassion, justice, and wisdom.
So, the core meaning of "virtue" is about being good, strong, and worthy of respect.