听不懂 don't understand (by listening)。
双语例句:
1、对不起,我听不懂你的话。
Sorry, I don't follow you.
2、我听不懂你的解释。
The explanation you give is beyond me.
3、我几乎听不懂他所讲的。
I understood little of what he said.
4、他谈到他的专业时,我就听不懂了。
He could not get through to me while he was talking about his special field.
5、我经常一点儿都听不懂他在说什么。
Half the time, I don't have the slightest idea what he's talking about.