My chest X-ray finding indicates: right apical pleural thickening and pulmonary hyperaeration. What does that mean?

Non specific. apical pleural thickening is non specific but can mean possible previous infection, most common is tuberculosis. Hyperaeration if a real finding is seen in asthma and COPD. Sometimes patients when told to take a deep breathe can over cooperate and simulate hyperaeration.
Many reasons. The pleura thicken for many reasons but most often due to infection or inflammation in the past. That includes many forms of bacteria and virus. The hyper aeration can be due to asthma such as that with allergies and even tobacco use amount others. It is best to talk to your doctor for more specific information.