According to the Radiologist,the lump in your left breast is possibly a complex Fibroadenoma.I don't think you should worry,because the findings do not indicate breast cancer.
Your biopsy report states that some cells are mildly"Atypical" meaning that they look a little abnormal.But this condition can be found also in benign lesion.
The radiologist has suggested removing the entire lump so it can be analyzed by a pathologist,just to make sure that there are not mixed type of cells that may increase your risk of breast cancer.
The surgery procedure is not complicated, and your recovery should be quick and uneventful.
In my opinion it's best to take this lump out of your body to be on the safe side and also to avoid more frequent screening in the future.
Regarding the specific terms used on your report,your doctor would be your best source of information.I am sure everything will be explained to you in details.
Wishing you benign findings on your upcoming lumpectomy and final pathology results.
All the best!...