That is referring to the signal which the T.V. can handle. If it's an old T.V. then you may have problems running a 60Hz signal (black and white or rolling picture), but odds are you'll be fine. Most T.Vs these days are more than capable of dealing with 50Hz and 60Hz signals.

Also, if you're planning to use the gameshark to play NTSC games on an unmodded PAL console you're probably going to run into problems. Region-locking has nothing to do with the output signal.