Afield means at a far distance. When you go far afield, you travel a very long way.
If your job takes you halfway around the world, you can say that you work far afield, and if you and your siblings live on different continents, your family is spread far afield. You'll almost always see the word "far" before afield, since it describes long distances. The word was originally a contraction of the Middle English in felde, from the Old English on felda, "in the field."