A phrase is a group of words acting as a single part of speech and not containing both a subject and a verb. It is a part of a sentence, and does not express a complete thought. The phrases in the first two sentences of this page are italicized.
The first sentence contains five phrases: "of words," "acting as a single part of speech," "as a single part," "of speech," and "not containing both a subject and a verb." Except for the phrase beginning with as, all the phrases are acting as adjectives. The phrase beginning with as is adverbial.