The phrase Notice of Action is a phrase which is used to state when the United States Citizenship and Immigration Services sends you a receipt to notify you that your application has been received. The Notice of Action is an acknowledgement of receipt.
The Notice of Action arrives after you have applied for a Petition for Alien Fiance. This being an acknowledgement of receipt after you have applied for a K1 Visa or a K3 Visa where you have used a Form I-129F for a K1 Visa / Fiancee Visa or had used a Form I130 for a K3 Visa / US Spouse Visa. The NOA 1 also gives you the date and case number for your application.
If you have used a lawyer for this then the lawyer will also be notified of the process as they would have filed a Form G-28 which allows them to be notified of the application for the visa and that it has been received.
The Notice of Action 1 is when the USCIS acknowledges receipt of the application and Notice of Action 2 is when they have approved it and set it on to the National Visa Center for further processing.