if the queston comes as Varno ke sarthak samuh ko kya kehte hain?
It means what is the collection of the hindi / devnagri letters .
Note that Sarthak means meaningful- so a collection of varn may not be meaningful .
Only if the collection of varna is meaning ful it becomes Shabd else it is subset of varnamala.
शब्द वर्णों या अक्षरों के सार्थक समूह को कहते हैं। शब्द: शब्द वर्णों या अक्षरों के सार्थक समूह को कहते हैं।
So for the question to
Varno ke sarthak samuh ko kya kehte hain
Varno ke sarthak samuh ko SHABD kehte hain.