What kind of property is this? Real estate or something else? Who are his relatives? Wife, kids?

Property belonging to a deceased person who dies without a will becomes part of their estate. The estate goes to their legal heirs. With no will the legal heirs are determined by local inheritance laws.

Note: ANY question on law needs to include the general locale as laws vary by area.

Yes, with no will ( and no more info than given) the estate owns it at this point and the heirs can make claim to the estate after all debts fro the estate are paid