That's a whopper of a link, so here's what its various components do:
This method does the actual pop up, and is included in the onclick attribute before the "return false" statement. The first of the three parameters to the window.open method, this.href, designates the page that loads into the popped-up window. It is literally this link's href. The second parameter, '_help', designates the html target name for the new window. It corresponds to the target="..." attribute mentioned below. The third parameter accepts a comma-separated string of window attributes, such as whether to include scrollbars or allow resizing. Omit the entire parameter and all the attributes are included. Include the parameter and only the attributes you list will appear.