Simply put its the average level of your blood sugar over the past 2-3 months (depending on how fast your blood renews itself).
It's the main diagnostic test for Type 2 in the NHS in the UK Under 42 is non diabetic 42-47 is considered "pre-diabetic", 48 and over will usually result in a diagnosis of Type 2. http://www.diabetes.co.uk/forum/threads/what-is-hba1c-reading.123938/
Hi @umvoti and welcome to the forum. It is all quite confusing when you are first diagnosed, but you will get a lot of good advice and support on here. Do you know what your HbA1c test figure is? If not you should find out from your GP surgery - they might also be online if your surgery has online access to your medical records.