％。
She paid 7% interest on the loan.
Literal
She [topic-は] that loan [on-に] 7% [genitive-の] interest [object-を] paid.
~に利子を払う ('pay interest on X') uses に to mark the loan that the interest is owed against — the same に of target / recipient that shows up in ~に支払う patterns broadly. ローン is a loanword from English 'loan'; in financial Japanese it specifically means a consumer or housing loan, while older Sino-Japanese 借金 ('debt') leans more general or colloquially negative. The ７ in ７％ here is the full-width digit, common in Japanese text for compatibility with the surrounding kanji and katakana — visually balanced, distinguishable at a glance.