It would be best for you to ask your doctor, the doctor who ordered the CT scan, to explain. Interpretation of both focal pleural thickening and tiny subpleural nodules would require additional information, most importantly, your symptoms and why the CT scan was done. Whether any of this was visible on your plain chest x-ray and, if so, was that x-ray compared to previous chest x-rays? Both findings probably represent scarring in response to an infection, sometime in your past, and if so, that is of little consequence. Bottom line, you do need to discuss this with your doctor and consider discussing it with the radiologist. They are in the best position to interpret the findings.