be completely at sea;beside (/wide of) the mark (/point); fail to get the gist (/hang); fail (/unable)to grasp the essence(/main points); impertinent; inconclusive; lose the thread of; make neither head nor tail (of sth); not see what sb is driving at ❍ 你刚才所说的话～。What you have just said is beside the point. ❍ 他讲了两个钟头，但是他的话让人～。He talked for two hours but his remarks were neither here nor there.
不得要领
fail to grasp the main point; be not to the point
不得要领bù dé yào lǐnɡ
没有掌握住事物的要点或关键。fail to grasp the main points, not see what sb. is driving at, beside the mark, in conclusive impertinent, be completely at sea