We have all known the frustration of being told to press Control-Option-Command-Shift and some other letter—most of us don’t do daily finger exercises to prepare for such nimble maneuvers. Apple’s Sticky Keys option can help with that. An adjacent feature, Slow Keys, can assist when your typing style and your actual results are out of sync.
Both features are found in System Preferences > Accessibility > Keyboard. In the Hardware tab, you can enable either Sticky Keys or Slow Keys or both and set their parameters.
Read more at Macworld.com