get in over your head什么意思 习惯用法，不要硬翻

The analogy is to an unskilled swimmer who has fallen into water that is too deep.
You are in over your head when you face a challenge you are not able to meet.
原先是指游泳新手掉进过深的水里。引申使用，指陷入无法应对的局面。
例句：1.The new PR Manager felt like she was in over her head during her first week at the new job.
{"Over one's head" refers to the depth of the situation one is in. The situation has become more serious (severe) than the person is prepared for. }
2.Go ahead and lead the meeting today; I'll help you out if you get in over your head.

所以前一位amazing0924翻译为“力不从心”，正解。

力不从心