Meaning: This sentence describes the speaker moving on foot at a fast pace towards a place where goods are sold.
Choice of Words: The word "I" is a pronoun that refers to the speaker. "Walk" is a verb that describes the act of moving on foot. "Quickly" is an adverb that indicates a fast pace. "To" is a preposition that indicates a destination. "Store" is a noun that refers to a place where goods are sold.