My doctor said my mammogram was suspicious -- what did she mean?

Needs evaluation.: Anything outside of normal or benign needs to be evaluated by further imaging and/or a second opinion with a surgeon specializing in breast disease. The use of the term "suspicious" often means a biopsy may be needed to rule out cancer. Always good to get an accurate diagnosis then you can decide how you want to deal with health challenges.

Depends: If it was a screening, it means you need to return for more imaging because a radiologist saw something that didn't look completely normal. If there was a suspicious finding on follow-up imaging, you will need a biopsy to get an answer.

Suspicious finding: Technically a suspicious(BIRADS category 4) breast lesion carries a chance of malignancy between 2-95%. This is unfortunately a wide range, but this classification is mandated by the Mammography Quality Standards Act(MQSA). Generally these lesions require biopsy, and as mentioned in another answer, about 75% of the biopsies turn out to be benign.