。
She speaks her mind frankly.
Literal
She [topic-は] frankly thing [object-を] say.
率直 ('frank, straightforward, direct') is a positive descriptor for honest speech — not blunt or rude. 率直に is the adverbial form. ものを言う ('to speak, talk,' literally 'to say things') is a slightly more formal alternative to just 言う, suggesting meaningful or deliberate speech. Reads as character description praising honesty.