There are a few possible meanings for "Nísia":
* A combination of the elements "ní", meaning "nothing" and "sia", meaning "being": This would translate to "non-being" or "emptiness", though this interpretation is not widely accepted.
* A diminutive form of "Nice": "Nice" is a popular name in some European countries, and "Nísia" could be a diminutive or shortened version of it.
* Derived from "Nízia": "Nízia" is an Italian name of unknown origin, possibly linked to the Greek word "Nike", meaning "victory".
Therefore, the meaning of "Nilsa" is uncertain, but it's likely related to the name "Nísia" and potentially has a connection to concepts of "non-being", "nothingness", or "victory".