Jilla is likely an English diminutive or variant of Jill, derived from Juliana and associated with youthful or downy meanings.
Jilla is likely an English diminutive or variant of Jill, which itself comes from Juliana and shares in the older tradition of youthful or soft feminine names. The spelling gives the name a slightly more expanded, contemporary feel while keeping the familiar base intact.
It is a name that sounds small, bright, and approachable. Because it comes through a diminutive tradition, Jilla carries an easy intimacy. It feels less formal than Juliana and a little more playful than Jill, which makes it sound personal and affectionate.
Names of this sort often survive because they are simple to say and pleasant to hear. Jilla has that lightness, but it also retains the longer historical shadow of the Juliana family.