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.
hold one's own (in an argument)
to be able to defend one`s position in an argument
Although the woman's boss is very aggressive she is able to hold her own in any dispute with him.
List of common idioms, their meanings and examples of their usage in sentences
Idioms can be a powerful linguistic tool only when they are used in the right way in the right places.