What does Nu (ν) prefix mean?
It's a typo of some sort. The Greek letter nu (looks like an italic 'v') is not an SI prefix, but may have been mistakenly used instead of an 'n' (nano). There are other 'n' and 'μ' prefixes in the datasheet, so it is not clear why they are not typed in. Comparing to a similar device (ZVN4525Z), you can see that nA is the correct unit.
https://www.diodes.com/assets/Datasheets/ZVN4525Z.pdf