An idiom is a group of words, or in other words, a phrase that has a meaning other than its literal meaning of the words in it.
wind things up
to end, to finish, to settle
"Let`s wind things up now and then we can go home."
List of common idioms, their meanings and examples of their usage in sentences
Idioms are phrases which cannot be understood simply by looking at the meaning of the individual words in the phrase.