有句英文想知點解

Can I Get Back To You On That?

意思是: 回頭找你/給你 ; 再與你聯絡 ; 往後給你回覆 ; 遲些找你...

因為有 "On That" 在後面 = 關於那些 或 在那方面. (是這句說話的關鍵)

說者意思是問: "我可否把這些 (That) 回頭 "覆你" 或 "再說" 嗎?
(因為某些原因他現在未能給你 這些 (That) 答覆: 例如-需引證, 確認, 查核後 ; 在不肯定 或 在忙的情況下)

If you can't decide or have no answer yet for some issues. You can always say : "Can I get back to you on this/that?". It's a polite way to tell someone, you are thinking about it and will soon reply to his call.