"A person eats an orange and an apple."
Translation:Una persona come una naranja y una manzana.
While I agree that using "they" when referring to one person is not really correct, it is often used specifically to avoid disclosing gender. For example, "I have a friend. They told me that ...." If you had said he or she there, which would be grammatically correct, you would've given a huge clue as to which friend it could be.
I know you already know this, but I figured I would add some context for the non-native English speakers.