Frankly, I dislike him.

Literal

Frankly speaking, I [topic-は] him [subject-が] disliked is.

率直に言えば (if I speak frankly) is the conditional form of 率直に言う, an interchangeable variant of 率直に言って — both preface honest opinion. 嫌いです is the polite form of 嫌い (dislike) — direct content delivered in polite wrapping.