An easy way to think of albedo is that it's something like "how reflective the earth (or what's covering it) is". So the polar ice caps have high albedo, as could be seen in the "nighttime view of earth" pic a while back. So do clouds. Something like a coniferous forest would probably have low albedo.

Taking this one step further, you can actually define it as a number between 0 and 1, which describes how much light is reflected back. Here's another good defnintion from one of my clearer books: "Not all the energy impinging on the earth is absorbed. A fraction is reflected or scattered...the number is called the albedo of the earth and has a value of approximately 0.3." (That is, 30% of energy from the sun is reflected away from Earth on average.) (There are maps in this book, too, showing how it varies over different parts of earth.)