> 點明 is a word which means: point out; put one's finger on
Yes, "put one's finger on" is the (kind of) equivalent expression in English. However, the original meaning behind the Cantonese version of "點" is "light up," as in "lighting up a lantern." 點到明 literally means "light up till it is bright," and 點醒 literally means "light up till [you] wake up." To call someone a 牛皮燈籠 (calf-skinned lantern) is to imply someone "點極都唔明" (it is never bright no matter how much effort is spent on lighting it up).
I guess one can use 點明 as a verb, but I would not recommend it to a learner, as it is usually interpreted as a question which means "How do I understand?"
If you must express the same meaning, try to say 點醒 if you don't mind to sound accusatory (as you express an angry tone and imply that the other person is dumb). Or you can just say 解釋 (explain) without specifying whether the other person gets it or not, or say 講清楚 (said clearly) if you want to emphasize that you have done your part. The following are alternative ways of conveying a similar message.
我點醒你咋 (I am doing you a favor by waking you up) [connotation: you are dumb]
我解釋咗 (I already explained) [connotation: neutral, descriptive]
我已經講到好清楚 (I already said very clearly) [connotation: not my problem, at least not any more]
Yes, "put one's finger on" is the (kind of) equivalent expression in English. However, the original meaning behind the Cantonese version of "點" is "light up," as in "lighting up a lantern." 點到明 literally means "light up till it is bright," and 點醒 literally means "light up till [you] wake up." To call someone a 牛皮燈籠 (calf-skinned lantern) is to imply someone "點極都唔明" (it is never bright no matter how much effort is spent on lighting it up).
I guess one can use 點明 as a verb, but I would not recommend it to a learner, as it is usually interpreted as a question which means "How do I understand?"
If you must express the same meaning, try to say 點醒 if you don't mind to sound accusatory (as you express an angry tone and imply that the other person is dumb). Or you can just say 解釋 (explain) without specifying whether the other person gets it or not, or say 講清楚 (said clearly) if you want to emphasize that you have done your part. The following are alternative ways of conveying a similar message.
我點醒你咋 (I am doing you a favor by waking you up) [connotation: you are dumb]
我解釋咗 (I already explained) [connotation: neutral, descriptive]
我已經講到好清楚 (I already said very clearly) [connotation: not my problem, at least not any more]