A verbal noun is a noun that is derived from a verb but functions as a noun in a sentence. It often represents the action or state of the verb and can be formed by adding specific suffixes, such as -ing in English. For example, in the phrase "the running of the race," the word "running" acts as a noun. Verbal nouns can take on various grammatical roles, such as the subject or object of a sentence. They can also be modified by adjectives or used with prepositions. An example is "the act of swimming" where "swimming" is the verbal noun representing the action of the verb swim.