It is an adjective.
Meaning : honest and downright.It is used to specify a good character which is noble i.e used to indicate the most honest character which is morally upright.
It also means standing erect or upright.
Synonyms: honest, honourable, upright, respectable, reputable, high-minded, law-abiding, right-minded, worthy
Antonyms : dishonourable, crook
upstandingness - noun
1)He looked like an upstanding man but alas! Appearances were deceptive.
2)Be upstanding in the court when the judge enters.
3)She has an upstanding character which always demands respect from others.
4)An upstanding man is rare to find in today's scenario.