0.61 x 0.34 x 0.48 cm well marginated hypoehoic soft tissue mass is noted at right submandibular area representing a lymp node. what does it means?

Lymph node: Sounds like you have had an ultrasound. Sounds like they found a normal sized lymph node. An abnormal lymph node will typically be larger than 1 cm. Examine yourself monthly. If it is growing seek out medical care.

That is: a common place to normally have lymph nodes. The size alone is not sufficient to determine whether it is abnormal. The shape/morphology and other features such as symmetry help determine whether it is abnormal. So, just the fact that there is a lymph node there doesn't mean there is something abnormal. Talk to your doc about the results.