My sister was diagnosed with anll. What does this mean?

ANLL=AML. First of all, I am sorry for your sister. Anll or more commonly known as acute myelogenous leukemia- is a cancer of the white blood cells. It is the most common cause of acute leukemia- about 80%. Symptoms are caused by supression of normal blood cells by the leukemic cells-will include fever, fatigue, bleeding, bone pain etc. Treatment will be combination of chemotherapy +/- transplant if indicated.
Acute leukemia. Anll is usually known as aml, acute myeloid leukemia. This is an aggressive type of leukemia and usually requires intense chemotherapy for treatment.