Acquired data is data that you didn’t create yourself. You didn’t observe it, you didn’t transform it, you can’t personally speak to those aspects of the data’s provenance. Depending on where and how you got it, you might be able to find out some things about the data. For instance, Data Cards are a documentation practice in the data science community that addresses some of the kinds of questions and ambiguities that you would have access to if you had created the data yourself.