What Does It Mean?

You are correct!

From our dictionary:
je•june

(ji•jOOn'), adj.
1. without interest or significance; dull; insipid: a jejune novel.
2. juvenile; immature; childish: jejune behavior.
3. lacking knowledge or experience; uninformed: jejune attempts to design a house.
4. deficient or lacking in nutritive value: a jejune diet.