Here's a breakdown:
* Parenthetical: It means something that is inserted into a sentence as an aside or extra information.
* Phrase: A group of words that functions as a single unit within a sentence.
The commas indicate that the phrase is separate from the main sentence structure and could be removed without changing the sentence's overall meaning.
Example:
"The dog, a fluffy golden retriever, wagged its tail excitedly."
Here, "a fluffy golden retriever" is the parenthetical phrase. It provides additional information about the dog but is not essential to understanding the main idea of the sentence, which is that the dog wagged its tail.