Will this lens fit on a nikon d40?

It's an AF-S DX Nikkor 18-55mm f/3.5-5.6G ED lens. I found it for sale online, but I'm new to the whole SLR thing and not very confident about making decisions!

Yes. ANY Nikkor AF-S lens will work just fine on your camera

The AF-S 18-55 mm lens is the one that came with the D40.

Here is a link to all the lenses Nikon makes. Any of the AF-S lenses will work

http://www.nikonusa.com/...index.page

Yes. And the D40 is a nice camera to have.