What is a dependent close?

Do you mean a "dependent clause"?

In English grammar, it is a portion of a sentence that has a subject and a predicate but cannot stand on its own as a sentence.

For example, "The man who commited the crime was arrested by the police."

"Who committed the crime" is a dependent clause. It acts as a modifier of the Word "man."

"The man was arrested because he committed a crime." Here "because he committed a crime" is another dependent clause.