The word “soon” is an adverb.
Adverbs are words that modify verbs, adjectives, or other adverbs, providing context such as time, manner, place, or degree. In the case of “soon,” it indicates a time frame, telling us that something will happen in the near future. For example, in the sentence “I will call you soon,” the adverb “soon” describes when the action of calling will take place, signaling that it is expected to happen shortly.