The hint would be in the name:
Chronic Obstructive Pulmonary Disease.
You can quibble about it not being a "real" disease...
However, the person diagnosed with COPD is unlikely to be impressed.
It may be caused by Bronchitis, Emphysema, Asthma or Bronchiectasis etc.
Either way, the person is ill. He/She will have difficulty breathing and because of that He/She will have difficulty excreting the mucous that is produced normally anyway.
As a result, the person will have reduced lung capacity and an increased incidence of respiratory infection.
Unfortunately, as a result of the difficulty breathing and mucous retention, clearing the infection will take longer than usual, and many find the infection returns quite rapidly.
Antibiotic resistant strains of bacteria also make the treatment difficult.
Usual treatment will be bronchodilators to open the airways, of which there are several different drugs available...long or short acting.
Inhaled corticosteroids are frequently prescribed, to ease the inflammation.
In an acute exacerbation oral Corticosteroids may be precribed, such as Prednisalone, acompanied with high doses of antibiotics.
Either way, a person diagnosed with COPD is ill, the illness is incurable, and will cause them trouble for the rest of their life.