This is the 306th most frequent French word.
certaines
"Certaines" means "some" or "certain" (feminine plural).
Here, "certaines" specifies that the ideas she has are of a particular subset or nature without elaborating on their details.
Elle a certaines idées qu'elle n'aime pas partager.
She has certain ideas that she doesn't like to share.
"Certaines" indicates that not all answers were correct, but a specific number or group of them were.
Certaines des réponses étaient correctes.
Some of the answers were correct.
In this sentence, "certaines" is an indefinite adjective referring to a specific subset of people, emphasizing that not all but some individuals hold this preference.