Hi, I speak Polish as my parents came from there, but I am an English native speaker. So, although I am not fluent in Polish, I do understand and speak it fairly well, so am answering your question, as otherwise you may not get an answer. Oni and one both mean "they" Oni Both are 3rd person plural personal pronouns, Oni is for male gender and one for female and non personal. Examples, Ony sa wysocy (they (men) are tall) and one czytaja duzo (they,(females) read a lot). For impersonal pronouns, say books, one (Ksiazki ) CORRECTION from Mateusz, here "te"is better than "one". stoja na polce. I have no Polish accents on this keyboard but I hope that helps.

C'est très simple: Oni= ils (hommes) One= elles (femmes) ils sont très bruyants = oni .... elles sont très bruyantes= one ...