bang one's head against a brick wall从字面上理解是某人用头撞墙，但是随着时间的发展，有人将其引申为了如今的含义，用来比喻做某事徒劳无益；枉费心机；白费力气。

【例句】
I wanted to sort out this problem with him, but it was like banging my head against a brick wall.
我曾想跟他把这个问题给解决了，但结果徒劳无功。

Trying to reason with them was like banging my head against a brick wall.
试图和他们讲道理只是白费口舌。