This is the 5834th most frequent Turkish word.
söylemesi
The act of saying or expressing.
Here, 'söylemesi' is a gerund form indicating the action of saying something as being necessary or expected.
Söylemesi gereken şeyi unutmuş gibi görünüyor.
He seems to have forgotten what he was supposed to say.
In this context, 'söylemesi' functions as part of a gerund form referring to the act of singing the song.
Bu şarkıyı söylemesi gerçekten harika bir yetenek.
Singing this song is truly an amazing talent.
Here, 'söylemesi' is used in the context of conveying an idea or action related to speaking the truth.