What is the Output of code ? $( "div#first, div.first, ol#items > [name$='first']" )

This code performs a query to retrieve any <div> element with the id first, plus all <div> elements with the class first, plus all elements which are children of the <ol id="items"> element and whose name attribute ends with the string "first".  This is an example of using multiple selectors at once. The function will return a jQuery object containing the results of the query.

I fully support Saud Rashid answer

Nothing, an error... It's just a selector. If you want to ask what it will select, It will select div which has id first and any divs which have class first and the elements which have name attribute first and are children of ol with id items.