Idioms
An idiom is a group of words, or in other words, a phrase that has a meaning different from the literal meaning of the words in it.
Idiom:
on (someone's) behalf
Meaning:
acting as someone's agent, acting for the benefit of someone
Example:
I was able to sign for the registered letter on my wife's behalf.
List of common idioms, their meanings and examples of their usage in sentences
An idiom is a widely used saying or expression containing a figurative meaning that differs from the phrase's literal meaning.