In your case it is an object passed to your css function.
myObj={} // a blank object
Here you can use this too
myObj={'float' : 'right'} xxx.css(myObj);
Here is another example of object
var myObj={ 'varOne':'One', 'methodOne':function(){ alert('methodOne has been called!')} } myObj.methodOne(); // It will alert 'methodOne has been called!'
A fiddle is here.