Let's break it down:
* "Ko" is usually used as an interrogative pronoun, similar to "what" in English.
* "Sa" is a preposition meaning "in" or "at."
* "Bag on" seems to be a combination of the words "bag" and "on." However, it's not a common phrase in Chavacano.
It's possible you're trying to express something like:
* "What's in the bag?" - This would be translated as "Kua na'e sa bag?"
* "What bag is that?" - This would be translated as "Ko sa bag i yan?"
To help me understand your intended phrase better, please provide more context or the complete sentence you're trying to translate.