すみません、その言葉の意味が___。
Q. Which verb naturally completes 'I don't understand the meaning of that word'?
Translation
Sorry, I don't understand the meaning of that word.
Explanation
分かる means to understand/grasp and takes が for the thing understood. 知りません means 'I don't know (have no information)' and can sound blunt; with 意味が, the natural verb is 分かりません.