The grammar is AはBがC meaning “As for A, B is C”. It’s used when you introduce the topic A and describe what A does or what A is like.
The declarative だ can be added which sounds more confident and assertive whereas it sounds softer without だ. In polite speech, simply add です.
Here are some examples:
- 私は月曜日が休みです (literally “As for me, Monday is my day off”) – “I have a day off on Monday”.
- 田中さんはテニスが趣味です (literally “As for Mr. Tanaka, tennis is his hobby”) – “Mr. Tanaka’s hobby is tennis”.
So 泥棒は盗むのが商売 literally is “As for thieves, stealing is their business” saying “thieves’ business is stealing” or “stealing is what thieves do best”. Let’s look at each word:
The A is 泥棒 meaning “thieves“.
The B is 盗むの meaning “stealing”. A verb plain-form followed by the nominaliser の works as a noun.
The C is 商売 meaning “business” or “trade”. It can be replaced with 仕事 meaning “work” but 商売 sounds more entrepreneurial whereas 仕事 sounds more like an employed job.
The grammar is たとえ A が B でも meaning “even if A is B”. Only “A が B でも” also means “even if A is B” but たとえ emphasises that the statement is very hypothetical.
The A is それ meaning “it” which indicates what thieves steal.
The B is 人の心 meaning “a person’s heart”.
So たとえそれが人の心でも means “even if it’s a person’s heart”.
And the last ね is the particle used to adjust the tone and draw the listener’s attention to the statement.
These clauses are actually inverted and the normal clause order without inversion would be たとえそれが人の心でもね、泥棒は盗むのが商売。By inverting the clauses, you can emphasise the subordinate clause as well as making the speech catchy or dramatic.