This is the 16528th most frequent Polish word.
winni
"Winni" means "guilty" or "at fault" in English.
Here, 'winni' is used as an adjective meaning 'guilty', describing the individuals responsible for a wrongdoing.
Oni są winni tego przestępstwa.
They are guilty of this crime.
In this case, 'winni' is used to denote an obligation, as 'we are obliged' or 'we owe it' to someone.
Winni jesteśmy wsparcia naszym przyjaciołom.
We owe support to our friends.
Here, 'winni' functions as a noun substitute, referring to those who are blameworthy or guilty of something.