[Q] What is the significance of receiving I-829 receipt notice from CSC?
First, it means your case has been received and inputted into USCIS computer system.
Second, I-829 receipt notice is a documentary evidence that allows you to work and travel for one year. [That's what the receipt says.] However, if you or your family member intends to travel outside the U.S., we recommend that you make an Infopass appointment with USCIS Field Office and get I-551 stamps in your passports.
Third, you can track status of your filed I-829 case by typing in the receipt number into the Online Case Status Check system at www.uscis.gov site.