Mythology is the study of folklore stories from particular cultures or religions. Myths generally deal with gods and demigods and their interactions with humans, and they often tell stories that attempt to explain creation and aspects of the human condition. You can also find mythological stories about humans who are exceptional or even noble yet not necessarily divine. Additionally, myths often relate the stories of a hero's journey and its ups and downs. Though we usually equate mythological stories with fiction, myths can actually tell true stories too. When we talk about mythology, we tend to think about ancient cultures, like the Greeks, Romans, Egyptians, or Norse, but myths can have more recent origins as well. Mythological stories can tie in with historical events, or they can have settings that don't have parallels here on earth.
Mythology is important because it gives us glimpses into how other cultures think and believe and because myths are simply fun and rewarding to read. If you read mythology alongside historical accounts of the nations and cultures that originated those myths, you get a picture of how those people interpreted the world in which they lived. Tracing the common threads of myths can give you an understanding into how cultures make sense of the world around them, even when they express things differently from other cultures. Mythology also helps you grasp the foundations of religious beliefs in various cultural contexts. Even though most myths deal with cultures from a different time and place, they can have parallels to your own life. For example, reading the hero's journey myths can help you understand how to approach your own struggles with determination and courage. Myths also tell rollicking and fascinating tales that are enjoyable to read, which may be the best reason of all to read and learn mythology.
Mythology is a fascinating and complex subject, and online courses on Coursera help you gain a thorough understanding of the stories and concepts behind the myths of different cultures. You can take courses that cover the basics of mythology, or you choose from any number of more specific mythological topics like myths that involve plagues and witches or how mythology relates to psychology.