Possibly from the German city Jena, or a modern variant of Jenna from Jennifer.
Jena is a phonetically streamlined variant of Jenna or Jana, names ultimately rooted in the Hebrew Yochanan (meaning "God is gracious") through its many European evolutions — Jane, Jean, Joanna, and their diminutives. The anglicization Jenna became widely popular in the English-speaking world during the late 20th century, and Jena represents a cleaner, more modern spelling that preserves the same warm, simple sound.
Jena is also the name of a historically significant German city in Thuringia, forever associated with two pivotal moments in intellectual history: the Battle of Jena in 1806, where Napoleon decisively defeated the Prussian Army, and the University of Jena, which in the late 18th and early 19th centuries was a hotbed of German Idealist philosophy — Hegel, Schiller, Fichte, and the Romantic poets all passed through or taught there. The name thus carries, for those aware of it, a faint resonance of intellectual revolution. In American popular culture, actress Jena Malone — known for her intense performances in films like "Donnie Darko" and "The Hunger Games" — has given the spelling a contemporary touchstone.
The name sits in a comfortable middle ground: familiar enough to feel friendly and approachable, distinctive in spelling enough to feel individual. It is a name that wears its simplicity as a virtue, never demanding attention but always quietly pleasing.