This is the 50th most frequent Turkish word.
ama
"Ama" means "but" in English.
Here, 'ama' is used to introduce a contrast between the desire to read the book and the lack of time.
Bu kitabı okumak istiyorum ama hiç zamanım yok.
I want to read this book, but I have no time.
In this case, 'ama' contrasts the option of inviting and the assumption of his lack of willingness to come.
Onu davet edebilirim ama gelmek istemez diye düşünüyorum.
I could invite him, but I think he doesn’t want to come.
Here, 'ama' is used to contrast the pleasant weather with the decision not to go out.