If you go to bhphotovideo.com and look up a lens, click the features tab of the product description. It will decipher all of the abbreviations for you.
For a starting point, DX lenses are built for cameras with sensors that are the size of the one in the D60. The FX lenses
can work on the D60 but are built for 35mm sensors and are generally more expensive.
As for the numbers.. one is focal length and the other is aperture. The aperture number(s) is given with an "f/" or "F" in front of it. Check out the sticky by poseidon on
Depth of Field and the one by Junior that covers
the basics. Those will give you a practical understanding of aperture.