My wbc is 2.7 k/ ul neutrophils 34% lymphocytes 50% haemoglobin 10.4gm/dl what does this mean? what can be the cause?

A little low: The neutrophils are a little low but it's not life-threatening. For some folks this is genetic. For some folks, it's cyclic. It can be from stress, medication allergy, or nobody-knows-what. How do you feel otherwise? Your phsyician will do the follow-up

Need for evaluation: What is your platelet count? If that is low too it is likely to be a bone marrow issue and warrants investigation by a hematologist. It would be prudent to see your doctor at the earliest and if needed seek consultation with a hematologist.