I forgot the original words, probably in the preface of the pure batch. It means: not making knowledge conform to the object, but making the object conform to the knowledge.

In other words, people generally believe that truth is the fact that makes their own understanding conform to the object, but Kant believes that it is impossible for us to know the thing itself, and what we know is the phenomenon processed by our ideological structure. So what we can know should be our ideological structure first.

The object here is the content of thought, and knowledge is the form of thought, that is, twelve categories.