。
We would appreciate your candid opinion on this matter.
Literal
This-matter about-[attributive-の] frank [honorific-ご]opinion [object-を] [honorific-お]let-hear-please.
A formal business/official phrase. 本件 ('this matter, this case') and ~についての ('concerning / about,' the attributive form of ~について) are formal vocabulary. ご意見 uses the honorific ご- prefix on a Sino-Japanese noun (ご-/お- with Sino-Japanese vs. native-word distinction). お聞かせください is the honorific request form — literally 'please honorably let us hear' — built as お + 聞かせる (causative of 聞く, 'let hear') + ください ('please'). This お~ください honorific request pattern is standard in polite business Japanese.