The suffix "-ly" is commonly added to adjectives to form adverbs, which describe how an action is performed. For example, the adjective quick becomes the adverb quickly, indicating that something is done in a quick manner. This transformation helps to provide more detail about verbs in a sentence. In addition to forming adverbs, "-ly" can also be used in some adjectives, such as friendly or lovely. These words describe qualities or characteristics. Understanding the use of "-ly" can enhance both writing and speaking by allowing for more precise descriptions of actions and attributes.