1. The problem is to understand the meaning and usage of the word "quickly" in English. 2. "Quickly" is an adverb that describes how an action is performed, meaning to do something at a fast speed or in a short time. 3. It modifies verbs to indicate the speed of the action, for example, "She runs quickly" means she runs fast. 4. Important rules: Adverbs like "quickly" often end in "-ly" and answer questions like "how?" or "in what manner?" about the verb. 5. Example: "He finished his homework quickly." Here, "quickly" tells us how he finished his homework. 6. In summary, "quickly" is used to describe the speed of an action, making sentences more descriptive and precise.