I am programmer and want to say "The programming language I have never used before" in very short word like "... programming language" What could that be?
There are a few alternatives involving prepositions:
I am unfamiliar with / illiterate in / ignorant of / incognizant of / inconversant with this programming language.
As mentioned, unfamiliar can also be used directly as an adjective applying to the programming language. The "to me" is then implicit in the meaning.
unfamiliar - This is an unfamiliar programming language to me.
You could try
I am a novice/neophyte/newbie/virgin in this programming language.
If you wished to indicate that you were not experienced, but dedicated to learning the language, you might say
I am an acolyte/apprentice in this programming language.
[Note: Before I am inundated by the Slash Police, I am not advocating the use of "/" in actual sentences, but merely suggesting a choice.]