The term "chops" actually was first a reference to horn players. It means jaws or mouth.
But, over the years, it has been applied to other forms of performance. In a musical sense, it is that thing, ability or technique that produces the music.
A drummers hands, technique, and ability to play would be considered "chops".
A singers's voice and ability to reach high or low notes, or the ability to "bend" or stretch" notes would be considered "chops".
A keyboardist who could play a difficult run very fast would be considered as having "chops".
So basically, if you can play, you have "chops". Now whether you play well or not, determines whether or not your "chops" would be referred to as good, bad, great, etc...
Hope this helps