What does "very rare atrial and ventricular ectopy" mean as a conclusion to a holter monitor report?

Probably normal: It is very common for most people to have some extra heart beats on a holter monitor. These ectopic or skipped beats could originate from the upper heart chamber (atrial) or lower heart chamber (ventricular). If these are isolated / single beats and infrequent, they usually are benign and not a concern and do not require further treatment. Call you doc if you have further questions.