。
She's quite a beauty.
Literal
She [topic-は] quite-the beauty is.
たいした is a complicated little word. Attached attributively to a positive noun (たいした美人, たいした腕前 'considerable skill'), it means 'considerable, quite a, remarkable.' Attached to a negative or downplaying noun (たいしたことではない 'no big deal,' たいしたものじゃない 'nothing special'), it means 'much of, all that much,' negating the claim of significance. So たいした美人だ here is approving — 'a real beauty.' 美人 (びじん) is the standard Japanese noun for 'beautiful person,' typically (but not exclusively) referring to women. The plain copula だ keeps the register conversational, almost evaluative.