When a person dies somebody has to deal with their estate.  A person's estate is made up of the money, property and any possessions they owned at the time of their death.  The process of Probate means verifying the validity of the Will, collecting any money that is owed, settling any debts due (including outstanding taxes) and dividing the estate amongst the respective beneficiaries.

Most assets (including property) in a estate will remain frozen, until the Probate Registry gives authority (via a document known as a Grant of Representation) to the Executor being the person nominated in your Will to deal with your affairs.  If you have no Will, then it is up to appropriate members of the family to act on behalf of the estate. 

If there is a Will the estate will pass to the people named in the Will. If there is no Will certain rules known as the Rules of Intestacy will apply.