。
I'm sure she's right.
Literal
She [topic-は] surely is-right [explanatory-のだろう].
A nicely compact prediction sentence layering きっと (high confidence) + ~のだろう (explanatory probability). The のだろう combination — の (explanatory nominalizer) + だろう (probable) — gives a tone of 'the situation must be that...' rather than just 'probably.' The speaker is reasoning toward an explanation, not just guessing. 正しい ('right, correct') is an i-adjective and slots into the predicate position with no copula needed before のだろう. Common pattern for 'I bet she's right' / 'must be that she's right.'