。
She still takes her teacher's words to heart.
Literal
She [topic-は] teacher [possessive-の] words [object-を] still heart [in-に] is-keeping.
心に留める (こころにとめる) means 'to keep in mind' or 'to take to heart' — treating something as memorable and worth holding onto. 留める (とめる) literally means 'to fasten' or 'to fix in place,' so the image is of fastening words into one's heart. The まだ ('still') emphasizes that these words continue to resonate long after they were spoken.