Passive loss carryovers happen when you weren't able to fully deduct business losses on your previous tax returns due to passive loss limitations.
If you couldn't deduct all of your losses from a K-1 on previous returns, you can enter the amount of your carryover here.
If you have passive income from your K-1s, part or all of the prior year passive losses can be used on this year's tax return. Otherwise, the passive losses will be reported again on your Form 8582 and will carry forward to next year. Passive losses continue to carry forward until you either have passive income to use the losses or you dispose of your ownership interest. In the year you dispose of your ownership interest, all passive losses including carryforwards are deducted.
Look for your prior year passive loss carryovers on Form 8582 of your prior year tax returns. Unallowed losses on Form 8582 Worksheets 5, 6 or 7 are the losses that carry forward to the next year.