Jambudweep (Jambudvipa) is not a span of years. It is the central continent of the middle world (Madhya‑loka) in Jain cosmology. Time in Jainism is beginningless and cyclical, so Jambudweep is described as a place within this eternal cycle, not something measured in “years.” ( jainknowledge.com)

If you were asking about “years of human life” in Jambudweep’s Bharat Kshetra (our region), Jain tradition says human lifespan varies with the time‑cycle (āra). In the present era it is generally up to about 120 years, whereas in earlier eras it was far, far longer, and in later eras it becomes shorter. ( jainknowledge.com)

For simple overviews:

• Jambudvipa mentioned in Jain stories:
• Time units and cycles in Jainism: