A SLURL is a Second Life URL, a URL to a Second Life destination that can be embedded in a webpage.

The quick and easy way to create a SLURL is to visit the location of the SLURL you want to create in Second Life, click on 'Map', and then click on 'Copy SLURL to clipboard' (lower right of the window).  The SLURL can then be copied from your clipboard.

You can also create your own SLURL by typing the following, and substituting the appropriate Region Name and X, Y, Z coordinates:

http://slurl.com/secondlife/Info%20Island/123/94/35