Native to maritime Southeast Asia, it can also grow in temperate regions. It is a tropical, evergreen, perennial grass that is aromatic and grows up to 1.5 m tall (PFAF, Wikipedia)
The heart of the young shoots is cooked and eaten. The leaves and the essential oil are used in traditional medicine to relieve spasms and increase perspiration. It is also used to treat digestive ailments (it relaxes the muscles of the stomach and gut), arthritis pains, and various skin conditions. (Journal of New Sciences, Florajournal)
You can discover more about Lemongrass' medicinal properties and its chemical composition on PFAF, here and here.
In mythology, lemongrass could be used to ward off dragons, fend away evil spirits, and even break curses and hexes which may have been cast on the user (OutofStress). In magical traditions, lemongrass is associated with the planet Mercury, the element air, and is considered to be masculine in nature. The cleansing properties of lemongrass are useful in rituals intended to cleanse and purify, or shed light on dark corners or hidden issues. (Saje, Eclectic witchcraft)
More about the ethnobotanic side: Aromatic Studies, Florajournal
You can find Lemongrass cultivation details here