"They are selling apples."

Translation: Oni sprzedają jabłka.

[BradLoose]

What is the difference between oni and one?

[libella1]

oni = they (masculine)
one = they (feminine)

[immery]

oni - a group of people that includes one male person

one - a group of female persons, also pronoun for all plural nouns that are not persons

[Alex556721]

Confused. It asks to translate They are selling apples. There are 3 choices. I choose, one sprzedają jabłka and it says incorrect. But that jesteś sprzedają jabłka is the right answer

[Jellei]

"jesteś sprzedają jabłka" does not make any sense at all.

Remember that some exercises say "check ALL the correct answers". And a sentence with "they" will always have more than one correct answer, unless it's so detailed that something in the sentence actually mentions 'their' gender.