。
It seems she was beautiful when she was young.
Literal
She [topic-は] young days [contrast-は] beauty was [it seems-ようだ].
The は after 若いころ adds a contrastive nuance: she was beautiful in her youth (with the implication that this is no longer the case or that the present is different). Combined with ようだ, the speaker is both inferring about the past and subtly contrasting it with the present.