This is the 2108th most frequent Chinese word.
啥
"啥" means "what."
In this sentence, '啥' is used as a colloquial interrogative word equivalent to 'what', replacing the standard '什么'.
你在干啥？
What are you doing?
Here, '啥' is employed as an interrogative to casually inquire about function or purpose.
这东西是啥用途？
What is the purpose of this thing?
In this context, '啥' serves as a flexible interrogative within an expressive sentence structure, emphasizing the question about general knowledge.