Ultrasound shows liver is 16.5 CM sagittally. Liver is markedly echogenic and also heterogeneous and coarse. Whats this mean?

Fatty liver. Sounds like they are describing fatty infiltration of the liver.
Talk to liver MD. The liver may be enlarged and "markedly echogenic" is descriptive term used when looking at ultrasound image when the structure you're looking at is brighter than expected. This is commonly seen in the liver due to fatty infiltration. This can be completely reversible if the offending agent is found and eliminated. Most common: alcohol, hepatitis, certain medications, type ii diabetes/obesity.
See below. It sometimes depends on the ultrasound machine. Some older machines make everything echogenic and coarse. On a good machine, the findings may indicate fatty changes in the liver or cirrhosis. Please follow up with your doctor on recommendations. A liver function test may help. Sometimes a ct of the abdomen may help.