This is the 4063rd most frequent Turkish word.
gülen
"Smiling."
In this context, 'gülen' is used to describe the woman who is smiling.
Pencereden dışarı gülen kadın, manzarayı izliyordu.
The woman smiling out of the window was watching the view.
In this sentence, 'gülen' is used as a participle to describe the child who is smiling.
Gülen çocuk mutlu görünüyordu.
The smiling child looked happy.
Here, 'gülen' functions as a participle to describe people who smile.