This is, unfortunately, one of the most overused buzzwords in the industry. But object-oriented design is very powerful because it facilitates the clean definition of interfaces and makes it possible to provide reusable "software ICs."--The Java Language, An Overview
Simply stated, object-oriented design is a technique that focuses design on the data (=objects) and on the interfaces to it. To make an analogy with carpentry, an "object-oriented" carpenter would be mostly concerned with the chair he was building, and secondarily with the tools used to make it; a "non-object-oriented" carpenter would think primarily of his tools. Object-oriented design is also the mechanism for defining how modules "plug and play."
Furthermore, Java is fully object oriented. Unlike C++, there are no functions hanging around in global space to do everything you forgot to do inside a class. Everything in Java is either an object, a class, or part of one. Java takes object oriented programming much more seriously than does C++.
Bottom Line: A+