Is she really going out with that tall, gorgeous guy?
The underlined phrase is -

• The Sentence: Is she really going out with that tall, gorgeous guy?
- The underlined part is - Prepositional Phrase.
- Prepositional Phrase সাধারণত -- to, of, about, at, before, after, by, behind, during, for, from, in, over, under, and with - preposition দ্বারা শুরু হয়।

• Prepositional Phrase:
- যে Phrase- Preposition দিয়ে শুরু হয়, কিন্তু Adjective বা Adverb এর কাজ করে, তাকে Prepositional Phrase বলে।

Other examples:
- A man of high intellect often feels lonely. (Prepositional Phrase/ Adjective Phrase)
- He went there with a jolly mind. (Prepositional Phrase/ Adverb Phrase)

Source: A Passage to the English Language, S.M. Zakir Hussain.