‘Throughout the Old Testament the Bible uses the word “repent”. God is said to repent. People are said to repent. The Hebrew word used is nacham. This word literally translates to “sighs heavily”.
In the English language, we also have idioms for repentance: “My boss did a 180 this morning about his position on smoke breaks”. “180” refers to the degrees it takes to turn around. Turning around might be physical, but it can be idiomatically applied to mental activities. No English speaker would assume that the boss in the example would physically turn around.
In the Hebrew language this image of someone “sighing heavily” figuratively meant repentance. When someone makes a deep mistake and wishes to change their actions, they might deeply sigh. This deep sigh was a sigh of exasperation, indicating a change of heart and change of actions. As a result, the Bible uses the word to idiomatically symbolize repentance.’
source: Chris Fisher (realityisnotoptional).