。
The lotus flowers were giving off an indescribable fragrance.
Literal
Lotus [of-の] flowers [topic-は] in-some-way [cannot-say-えない] fragrance [object-を] were-giving-off.
なんとも言えない is an idiomatic construction literally 'in no way sayable' = 'indescribable, beyond words.' The ~を放っていた combines the literary verb 放つ ('release, emit') with the past-progressive, producing the 'was giving off' reading — stately, book-ish tone. Lotuses (蓮) carry strong Buddhist connotations in Japanese literature.