Thyroid U/S showed L thyroid gland heterogeneous hypoechoic nodule w/ mind internal vascularity. What does all this mean? FNA recommended.

Means abnormal test. Ultrasound is a commonly used test for detection of Throid nodules which are quite common. So when the ultrasound shows a Thyroid nodule, it needs to be monitored and often a Biopsy is required to find out if the nodule is benign or cancerous. FNA is one such technique for obtaining a biopsy for making a diagnosis.