I have a lump on my neck over a year is about 1cm.i have no other problems. tooday doctor suggest me its lymp nodes. suggest me for fnac.is serious?

Nodes: Nodes are very common but having a fine needle aspiration is a good idea to be sure its nothing serious

Neck mass: We don't know if its serious, which is why your doctor has ordered a fine needle aspiration biopsy (I presume you meant fnab). Its only 1 cm and stable for a year with no other symptoms (you are likely lean), it is unlikely to be a serious pathology. Likely reactive to a local inflammation which resolved but the node remained slightly enlarged.

A biopsy: A biopsy which is quick and easy will give you the answer.