A phrase is a group of words that forms a unit simpler than a sentence. Unlike a sentence, or clause, a phrase normally does not contain both a subject and a finite (conjugated) verb. When building sentences, we use many types of phrases. This article focuses on noun phrases.
A noun phrase is simply a noun (or pronoun) with its modifiers.
Noun phrases can contain adjectives, phrases or even dependent clauses that modify the noun:
those two old pickup trucks
[adjectives those, two, old and pickup + noun trucks]
trucks with rusty fenders
[noun trucks + prepositional phrase with rusty fenders]
trucks carrying food and supplies
[noun trucks + participle phrase carrying food and supplies]
trucks manufactured in Canada
[noun trucks + participle phrase manufactured in Canada]
trucks to haul firewood
[noun trucks + infinitive phrase to haul firewood]
trucks that have lower mileage
[noun trucks + adjective clause that have lower mileage]
Note: We have said that a phrase normally does not contain a subject and verb. The exception is a phrase that contains a dependent clause as a modifier, because every clause has a subject and verb.