be all ears的意思是“全神贯注地听；洗耳恭听”。

【例句】
If Japan can find a way of dealing with an ageing and falling population, its neighbours will be all ears.
如果日本能为老龄化和人口缩减开出良方，邻国们全都会洗耳恭听。

I'm all ears - tell us what they had to say.
我洗耳恭听——快告诉我们他们是怎么说的。