I just used chatGPT and this is what it said

The term "complex cyst" refers to a cyst that has both fluid and solid components, or internal structures like septations (dividers inside the cyst). While a complex cyst might seem more concerning at first, the BI-RADS 2 score indicates that the overall risk for cancer is extremely low, suggesting that the cyst is benign.

The BI-RADS system is used to classify breast imaging findings based on their appearance and likelihood of being cancerous. A BI-RADS 2 score specifically means that the abnormality is benign—no malignancy is suspected. So, even though the cyst is complex (which can sometimes raise concerns), it doesn't have features that would typically point to cancer, such as irregular shape, spiculated borders, or solid areas with suspicious characteristics.