。
She is kind to elderly people.
Literal
She [topic-は] elderly-people [to-に] kind is.
お年寄り is the polite, slightly euphemistic term for 'elderly people' — お adds respectful softening. Other terms include 高齢者 (formal/clinical, 'senior citizens') and 老人 (more direct, sometimes feeling blunt). 親切 ('kind') is a な-adjective taking に to mark the recipient of kindness.