「」。
On this point, one can only respond with "You are absolutely right."
Literal
This [about-については] "truly say [as-per-通り] [is-でございます]" [quotative-と] answer only [explanatory-のです].
A keigo-laden sentence with an embedded quotation. 仰る通り (おっしゃるとおり) is the honorific form of 言う通り ('as you say') — 仰る being the sonkeigo (尊敬語) form of 言う. でございます is the keigo copula, even more formal than です. ~しかない ('can only do X / there's no choice but X') frames the agreement as unavoidable — 'one has no choice but to say yes.' まことに ('truly / indeed') is formal-register emphasis. The sentence comments on a situation where complete agreement is the only appropriate response.