It's possible you're thinking of:
* The Kingdom of Tondo: This was a pre-colonial kingdom in the Philippines, likely centered around Manila Bay. It's possible "Lakan Dula" refers to a ruler of this kingdom, but there isn't sufficient historical evidence to confirm this.
* A fictional kingdom: Some stories or media might have created a fictional kingdom with that name.
Regardless, it's safe to say that there's no official language associated with this kingdom, as it is not historically documented.
If you can provide more context or details about where you encountered this term, I might be able to give you a more specific answer.