Complex sentence: About ten hymns in the "Rigveda" are accredited to Maitreyi, and she explored the Hindu concept of Atman (soul or self) in the "Brihadaranyaka Upanishad".
Split into simpler sentences: About ten hymns in the "Rigveda" are accredited to Maitreyi. She discusses the Hindu concept of Atman (soul, self) in the "Brihadaranyaka Upanishad".