。
She cut an apple with a knife.
Literal
She [topic-は] knife [with-で] apple [object-を] cut.
Identical structure to cutting one's hand, but with an inanimate object — the apple. リンゴ is technically a Japanese-native word (the kanji 林檎 exists), but it's so commonly written in katakana that learners often assume it's a loanword. This is a feature of katakana use in modern Japanese: native words can move into katakana for various effects, including emphasis, modernity, scientific register, or simply visual distinctiveness. Apples themselves are a major fruit crop in Japan, especially associated with Aomori Prefecture in the north.