我弄不清楚他是什么意思.
I couldn't make out what he was driving at.
《21世纪大英汉词典》
driving at 就可以表示她是什么意思
慢慢地领悟了 则是表示为gradually dawned on my mind
我渐渐地了解了实情.
The fact gradually dawned on my mind.
《21世纪大英汉词典》
所以整个句子是gradually,what she was driving at /what she meant dawned on my mind