Hi thanks for your question.
On left side there is obstruction in the upper part ureter
due to which upper ureter along with pelvis(part of kidney
into which urine comes after filtration from blood) of kidney is dilated.Cause of diltation not mentioned,could be a stone.
Echogenic shadow of 6mm means 6mm stone.Middle calyx is the part of pelvis of kidney.
The site of stone on left side is not mentioned,must be in upper part of ureter.
Hope this answers your question.