Once the US petitioner receives the NOA2 notice of Action Approval, the case will be forwarded to the National Visa Center (NVC). The NVC will then create the visa case number that the beneficiary will use in scheduling an interview appointment to the US Embassy. NVC will forward the visa case number to the US embassy nearest to the beneficiary where the interview will be held. When the US embassy receives the case number, they will send a letter to the beneficiary containing the case number, an instruction on where to do the medical examination and a government website link that will provide you the information on the forms you need to fill, things you need to do before the interview.
The letter shows your non immigrant visa case number, website link, applicant information. Another letter attached to the embassy mail is information about the medical examination and average timeline of visa issuance and delivery.
Another letter attachment is the copy of the i-129f petition approval letter. It is the copy of the I129f petition application that was previously submitted to USCIS.
The last attachment letter is the information about your rights from domestic violence and information on what you are going to do next after arriving in the United States. It is written in both your native language and in English.