If someone can't see the wood for the trees in British English, or can't see the forest for the trees in American English, they are very involved in the details of something and so they do not notice what is important about the thing as a whole.
如果某人can't see the wood for the trees（英式英語的説法），或者can't see the forest for the trees（美式英語的説法），那麼就是説他們非常關注某件事的細節，而導致他們不會注意到這件事的整體重要性。
Marcus is so focused on product details that he can't see the wood for the trees when it comes to the overall needs of the company.
馬庫斯太專注於產品細節，以至於當涉及到公司的整體需求時，他反而看不到了。