An acquisition is something you acquire—a book, a skill or if you are a mogul, a company. It describes things you have purchased, things you have learned, or things you have gotten.
Acquisition has a formal sense to it. We don't talk about our new jeans as our latest acquisition, unless we are the kind of person who refers to their latest copy of Vogue as their Bible. It is very commonly used to refer to paintings purchased by museums—in fact, large museums have acquisition departments.