If the disconnect is pulled in the cockpit, it physically disconnects the left and right control systems. In the case of the aileron, it's then pilot controls left aileron, co-pilot controls right. Without reconnecting the disconnect, there's no longer any connection to the "opposite side aileron"
edit to add that the disconnect is not the same as the "anti jam mechanism" - there is an "anti jam mechanism" in the rudder circuit - as there is only one rudder - whereas for aileron and elevator the disconnect option is used to isolate the jammed portion of the controls and leave some residual control capability