Your degree is what you will get upon graduation. You will actually have a paper diploma. There are a number of different types of degrees - associates degree (a 2-year degree), bachelors degree (4-year degree) and various postgraduate degrees like your masters degree or your Ph.D.
You will achieve your degree in your major field of study. For example, if you graduate from a university in which you majored in Psychology, you will have a bachelor's degree in Psychology. If you don't know what your major is, you're likely an "undeclared" major. That simply means you haven't decided what you want to major in, yet.
