The important question is what does your doctor think they mean? Or is the information from a home run test? If the latter it may be time to see a doctor.
In general bradycardia means the resting heart rate is below 40, I think it is 40, you can look it up. Many people live with a low HR, and of course the HR comes up when they begin to do physical work. Others have dizziness problems, do you suffer any symptoms?
The atrial issue may be PAC, Premature Atrial Contractions, another common heart rhythm issue most people live with, many without even knowing it. I, for example, suffer from Atrial Fibrillation, which means my atrial chambers are not really working and the only symptom I feel is an elevated HR and less physical endurance. I take beta blockers to lower the HR, which would be around 130 at rest due to the AFib, with the meds my resting HR is in the upper 70s. Just the opposite of your situation.