Breast ultrasound indicate 2 hypoechoic nodule with well defined margins. meaning?

Cyst?: This could be bening cysts. However you should have your dr either do fna for pathology or close surveillance.

Assessing: the margins is one of several US features that are used to decide the level of suspicion of a lesion. A well defined margin is generally considered a feature more indicative of a benign lesion. There are other features(e.g. shape, vascularity, shadowing) which need to be evaluated to form a complete assessment of the mass.