Sorry for not responding earlier, as I've just joined this forum. My main interest is in Kant, so I'm picking up on your question.
But I have another question in return.
Can you point out which work of Kant's you are referring to, and what section, chapter, or sub-heading. Then there will be something more to go on. As it is, the question is rather sparse.
Kant's idea of universality in reference to nature I think pertains to his idea of a priori judgments that have universal, objective validity. But without any further elaboration on your part I cannot comment any further.