This is the defintion from Wikipedia-the free encyclopedia: A verbal noun is a noun formed directly as an inflexion of a verb or a verb stem, sharing at least in part its constructions. This term is applied especially to gerunds, and sometimes also to infinitives and supines (full infinitive or to infinitive).
Yes, an infinitive has many uses which need to be eplained to the students by the teacher who has put the OP. I have only singled out its use in the example sentence
One thing is very clear from this, and that is that the greatest care needs to be exercised when we start relying on Wikipedia for our grammatical information: I know of no grammarian who would ever term an infinitive a 'verbal noun', and the supine, a form of the Latin verb, does not even exist in English grammar!