Adverb is a word which qualifies a verb and a phrase which does the work of an adverb is called as Adverb Phrase.
a. We can get those documents in an hour.
b. Sameer writes with artistic touch.
c. I shall purchase a pen from a shop in the corner.
If we ask question to verb, we get the answer that is an adverb.
In sentence ‘a’, ‘in an hour’ does not have subject and predicate and it tells us when we can get documents. So ‘in an hour’ is an adverb phrase. In sentence ‘b’, ‘with artistic touch’ also does not have subject and predicate and tells us that how Sameer writes. So ‘with artistic touch’ is an adverb phrase.
In sentence ‘c’, ‘from a shop in the corner’ also is without subject and predicate. It tells us from where to purchase. So it is an adverb phrase.