A garland is a circular arrangement of flowers, worn or hung for decoration. Think of the strings of pine and holly people hang at holiday time, or the ring of roses they put around the Kentucky Derby winner's neck.
First recorded circa 1300, the word garland in the simplest terms means a circle of flowers or other greenery. Hawaiian leis are a type of garland, as are holiday wreaths and the little flower crowns that flower girls wear at weddings. If you want to get spiritual about garlands, you can refer back to this Buddha quote: "Fashion your life as a garland of beautiful deeds."