A gerund phrase includes the gerund plus its objects, modifiers, or complements. Like a gerund, it is used as a nounas subject, subject complement, direct object, indirect object, object of a preposition, or appositive.
Editing my roommate's paper was a difficult task, [gerund phrase as a subject]
My editing was ruining our friendship, [gerund phrase as subject complement]
I prefer typing and proofreading papers, [gerund phrase as direct object]
The jury awarded her singing first prize, [gerund phrase as indirect object]
In addition to my editing her paper, she wanted me to revise it. [gerund phrase as object of preposition]
That particular job, editing her paper, was more stressful than I had anticipated, [gerund phrase as appositive]