The cycle~ object uses a lookup table of 512 values that make the shape of a single cycle of a cosine wave, and it reads through those repeatedly at whatever rate is specified in its left (frequency) inlet. You can also set the cycle~ to 0 Hz (its default frequency) and select a point in the cosine waveform with a value (either a signal or a float) from 0 to 1 in the right (phase offset) inlet.
This pan~ subpatch takes one signal in the left inlet, and sends it out each of two outlets. The amplitude gain for each outlet is determined by a panning value supplied in the right inlet. This value can be supplied as a typed-in argument in the main patch, as a float value, or as a control signal.