I do not have direct experience with either your breakout board or your drivers.
So this info is just based on my experience with other such units.
EN = Enable (the enable signal is supposed to be asserted in order for the driver to power the attached stepper motor)
CW = Direction signal (a high signal may signify "clockwise" direction, while a low signal may signify "counter-clockwise" direction, however the motor direction will also depend on the wiring to the motors)
CK = Step pulse (or clock) signal - one pulse on this line moves the motor one step (or microstep, depending on the mode set within the driver)