Basically your x-ray image shows that there is something in the left upper lung and I can only assume that by ill-defined densities they meant to say that there are no large changes in your left lung. There are number of reasons why you'd get x-ray results like these - from infection, tuberculosis or tumorous changes, just to name the most common reasons.
But you should get professional opinion on what these results mean and get the treatment you might need. It's really irresponsible for either x-ray technician or your doctor not giving you any explanation for your x-ray results mainly because there are pretty serious conditions that affect the lungs - and there are just harmless causes as well.
Wish you all the best,