get sth off your chest意为“倾吐心里的烦恼，吐出心事，一吐为快”。

【例句】
When Ann was going through tough times, he lent a sympathetic ear to her troubles.
当安正处于艰难时期时，他同情地倾听她的烦恼。

Sorry I'm late, I had to lend an ear to Jane. She's been going through a lot lately.
对不起，我迟到了，我得听简说。她最近经历了很多事。