。
A sensible person wouldn't talk to you like that.
Literal
Good-sense [of-の] existing person [if-なら] that-kind-of way [in-に] you [to-に] wouldn't-speak-caused [probably-だろう].
良識のある ('sensible, having good judgment,' literally 'having good sense') — the relative clause modifies 人. 話しかける ('to talk to, address'). ~ないだろう is the negative conjectural — 'probably wouldn't.' A value judgment about another's behavior.