Ardha pudgal paravartan kaal is the half measure of pudgal paravartan kaal, and it is an extremely vast, unimaginable time period in Jain cosmology.

In simple terms:

• Pudgal paravartan kaal = the time taken for all pudgals in the universe to completely circulate and return through all possible states.
• Ardha pudgal paravartan kaal = half of that immense duration.

It is used in Jain scriptures to describe very large cosmic time spans, especially in discussions of samsara and the wandering of the jiva.

Because it is a super-astronomical time measure, it is not practically expressible in ordinary years.

If you want, I can also explain:

• pudgal paravartan kaal
• ardha pudgal paravartan kaal
• or the full Jain time cycle in simple words.