They have found changed lymph nodes inside your chest cavity in front the part where the windpipe branches in two parts, and around the main blood vessels.
This intrathoracic adenopathy can be due to presence of malignant process, infection (usually, tuberculosis, and some fungal infections like histoplasmosis) and sarcoidosis, an inflammatory disease.
Since Ct scan can't differentiated between malignant and reactive lymph nodes, the follow up with repeated CT scan to check for lymph nodes size change is usually suggested.
Other exams like biopsy can revile the nature of adenopathy.
Best wishes!
Marija