More Words, Deeper Hole

on is tricky in French, and we don't really have an idiomaticly similar English pronoun. We say it's "one", and that gets close, but "on" is in much wider use than most English speakers would use "one".

To paraphrase from (https://en.wikibooks.org/wiki/French/Grammar/Pronouns#The_pronoun_on), French uses it for:

- Generalities about behaviour or identity ("To be a writer, one must write")

- Implicit subject for infinitive verbs ("penser qu'on a raison" --> the behaviour of believing oneself to be correct)

- Empty subjects in passive construction where agency is unimportant ("on me l'a donné" --> "where did you get that towel?" "Oh, somebody gave it to me.")

- Informal substitute for inclusive plural addressing: ("on y vas?" --> "let's go, now?")

That said, it really doesn't mean "one" where we have that overloaded in English -- it fills this really handy niche of expression where the subject's identity or gender might be assumed, contextually known, but really is not important, whereas, in English, it feels like we use "one" for indeterminate subjects but precisely where the identity is important ... that is, we use it as a polite way of saying "you, yes you", or "me, yes me"... for example "One really should be careful where one puts one feet, shouldn't one?"

I'm not sure that French uses "on" idiomatically that way much at all. But it's been a looooong time, and I'm not a native speaker, so I could easily be wrong.