Find the buy out price of your lease and compare it to how much you can trade/sell it for. Whatever the difference is, you'll either have to pay the difference or get money back. The other option is to get someone else to take over the lease, but I think with Volvo you'll still be responsible if that person doesn't make payments.
EDIT: It looks like Volvo doesn't allow lease transfers, so your only option is to sell/trade and hope it's not upside down.
https://www.swapalease.com/help/leas...ncial-services