The suffix "ly" means having the nature or qualities of something, such as brotherly, honestly or mightily. It can also mean to have a certain degree of something, such as hourly, minutely or recently.
The suffix "ly" originated in Middle English and has roots with the Old English suffix "lic," which was derived from the Germanic suffix "lich." The most common use of the suffix "ly" today is in the use of adverb modifiers. It is an easy way to create adverbs from adjectives when a writer or speaker needs to help describe the actions of a verb more specifically than its meaning allows.