ref – https://www.grammar-monster.com/glossary/noun_phrases.htm

What Is a Noun Phrase?

A noun phrase is a group of two or more words headed by a noun that includes modifiers.

note:
adjectives and adverbs are modifiers
Phrases can also be modifiers

the dog
the = modifier

a cat
a = modifier

a group of them
‘a’ and ‘of them’ = modifiers

The best car safety device
‘The best car safety’ = modifier

the man with her

‘the’ and ‘with her’ = modifiers

Examples of Noun Phrases

*highlighted is the head noun

People: the soldier, my cousin, dopey Alan, the lawyer with the big nose

Animals: that aardvark, one rat, a shark, funny Mickey

Places: the house in the corner, inner London, dirty factory, no shelter

Things: this table, our London Bridge, the sharp chisel, that nitrogen, last month, an inch, her cooking

Ideas: utter confusion, some kindness, your faith, the Theory of Relativity, a joy

The Function of Noun Phrases

Like any noun, a noun phrase can function as a subject, an object, or a complement within a sentence. In each example below, the noun phrase is in bold and the head noun is highlighted.

Singing in the bath relaxes me.
Here, the noun phrase is the subject of the verb “relaxes.”

I know the back streets.

Here, the noun phrase is the direct object of the verb “know.”

She was the devil in disguise.
Here, the noun phrase is a subject complement following the linking verb “was.”

Example

This man has a nice smile,
but
he’s got iron teeth.

“This man” is the subject of the verb “has.”

The phrase “a nice smile” is the direct object of “has.”

The noun phrase “iron teeth” is the direct object of the verb “got.”

Example

I (subj) never learned (verb) from (preposition) a man who agreed with me.

The noun phrase “a man who agreed with me” is the object of the preposition “from.”

Here’s the “pronoun test”: I never learned from him.

him – a man

Example

Every man of courage is (linking verb) a man of his word.

“Every man of courage” is the subject of the verb “is.”
The noun phrase “a man of his word” is a subject complement following the linking verb “is.”

Here’s the “pronoun test”: He is one.
He – Every man
one – a man

Example

The best defense against (preposition) [the atom bomb]
is (linking verb)
not to be there when it goes off.

First, the linking verb ‘is’ signifies that what came before is the subject,
and because it has modifier ‘the best’ and first noun ‘defense’, then its a noun phrase:

The best defense

But, there is a noun phrase within a noun phrase.

The noun phrase “the atom bomb” is the object of the preposition “against.”

The prepositional phrase “against the atom bomb” modifies “defense.”

Example

I don’t have (verb) a bank account,
because
I don’t know (verb) my mother’s maiden name.

In this example, both noun phrases are direct objects.

Example

The best car safety device is (linking verb) a rear-view mirror with a cop in it.

(In this example, the first noun phrase is the subject, and the second is a subject complement.)

Only two things are infinite, the universe and human stupidity, and I’m not sure about [preposition] the former. (Physicist Albert Einstein, 1879-1955)