Is there an idiomatic way to express being overwhelmed by vocabulary?
无从说起：
指事情太繁杂，要说的话很多，但不知道该从哪里说起。
Things are too complicated and there are many things to say, but don’t know where to start.
一言难尽：形容事情曲折复杂，不是一句话能说清楚的。
Describe things tortuous and complex, a sentence cannot make it clear.