This is the 4887th most frequent Russian word.
кажутся
"Кажутся" means "seem" or "appear."
Here, 'кажутся' conveys the speaker's impression about the buildings' height.
Эти здания кажутся очень высокими.
These buildings seem very tall.
In this sentence, 'кажутся' reflects the personal perception of the sincerity of the words.
Твои слова кажутся мне искренними.
Your words seem sincere to me.
'Кажутся' here indicates an impression or thought about the nature of her actions.