This is the 5833rd most frequent Turkish word.
söylediler
"They said."
Here, 'söylediler' is used as a past-tense verb indicating that 'they' conveyed some information verbally about the book.
Kitap hakkında olumlu şeyler söylediler.
They said positive things about the book.
In this sentence, 'söylediler' is employed to highlight that 'they' communicated their expected tardiness.
Toplantıya geç kalacaklarını söylediler.
They said they would be late to the meeting.
The usage of 'söylediler' implies the act of 'them' expressing their enjoyment regarding the new song.