At the end of your immigrant visa interview, the consular officer will inform you whether your visa application is approved or denied.
Some visa applications require further administrative processing, which takes additional time after the visa applicant’s interview by a consular officer. Applicants are generally advised of this requirement during their interview. When administrative processing is required, the timing will vary based on the individual circumstances of each case. You can check the status of your visa application on ceac.state.gov. Except in cases of emergency travel (i.e. serious illnesses, injuries, or deaths in your immediate family), before making inquiries about status of administrative processing, applicants should wait at least 180 days from the date of interview or submission of supplemental documents, whichever is later.
If your visa has been denied, you may find useful information on Ineligibilities and Waivers on usvisas.state.gov.