This is the 1755th most frequent Turkish word.
türkçe
Turkish language.
Here, 'Türkçe' is used as an adjective to describe the language of the course.
Türkçe bir dil kursuna katılmak istiyorum.
I want to join a Turkish language course.
In this sentence, 'Türkçe' refers to the Turkish language as the object of the verb.
Türkçe öğrenmeye başladım.
I started learning Turkish.
The word 'Türkçe' here specifies the language to be spoken in the sentence.