This is the 808th most frequent Turkish word.
hayatının
"Of your life" or "of his/her/its life."
The word 'hayatının' means 'of your life' and indicates possession in this sentence, referring to the person's life and its best times.
Hayatının en güzel dönemlerini yaşıyorsun.
You are living the best times of your life.
Here, 'hayatının' again means 'of your life', emphasizing enquiry into the personal meaning of one's existence.
Hayatının anlamını sorgulamaya başladın mı?
Have you started questioning the meaning of your life?
In this example, 'hayatının' is used as 'of your life', highlighting ownership and fullness of experiences in life.