The Notice of Sale is a document similar to the Notice of Default, which tells the borrower that the lender is beginning foreclosure proceedings against him. In most states, there is a period of time between the NOD and the bank sale where the borrower is allowed to cure the default and bring the loan current. In California MANY years ago, it used to be 90 days. After that, the sale is scheduled and the borrower notified of the fact.
If you need more specific information - http://ForeclosureIQ.com