。
She'll probably come tomorrow.
Literal
She [topic-は] probably tomorrow come [probably-でしょう].
たぶん plus でしょう is a redundant-but-natural double hedge — both elements mark probability, and Japanese routinely uses them together for a layered 'probably... I think' effect rather than choosing one. The polite でしょう (versus plain だろう) lifts the register a notch, fitting the kind of remark you'd make to a coworker or acquaintance about a third party's plans. Compare with きっと来る ('she'll come for sure'), 来るかもしれない ('she might come'), 来るはずだ ('she's supposed to come') — Japanese has a fine-grained set of confidence markers, and この sentence sits squarely in middle-range conjecture.