If breast biopsy report stated "benign breast tissue", what does this include? is fat and fibrotic tissue included? or just ducts.

Not just ducts: The breast is a mixture of fat, ducts, fibrous connective tissue, and other components. A biopsy does not selectively sample any one of those tissue types but rather is a mixture of all of them. Benign biopsy would indicate that no malignant components were found in the entire sample that was submitted.

Could: be all of the above, they comprise benign breast tissue.