"Hepatitis b patients usually recover completely and are immune" - Does this mean the virus is no longer in the body? Pls explain "recover completely"

No guarantees. You can recover and still have the virus in your system. If so, exacerbations of HBV can occur. Tests are available to determine if the virus, its antigens and its antibodies are present. Most people, after recovery, will remain asymptomatic. But, a few will develop late complications, like chronic hepatitis, cirrhosis, and liver tumors. You need follow-up by your physician or a liver special.