SELECT *
WHERE {
?Employee a :employee ;
SkillList:LastName ?LastName ;
SkillList:Location ?Location.
}
Some explanation on what's going on here. Namespaces are just a shorthand for writing out a long url. The prefix is replaced by whatever namespace you assign to it. You can always write out the full url surrounded by angle brackets to indicate that it's a url. Namespaces can be anything you want including an empty namespace which would be just a :.
As a convenience to the user Stardog automatically assigns this namespace to http://api.stardog.com/ . The user is free to change that if they like. As you can see in your query the :employee uses that namespace.
What may be somewhat confusing is that the properties LastName and Location are in a slightly different namespace, http://api.starodg.com#. Take note of the tailing # rather than a /.
You can either write out the complete url or define a namespace for http://api.stardog.com#.
In your example you defined prefix: SkillList, iri: http://api.stardog.com#SkillList which whould translate to the following prefixes for your query