The z~ object allows for delays of audio signal. The default delay for z~ is 1, corresponding to time of 1/44100 or about 22.7 microseconds.
If you want another amount of delay you have to write the number, such as z~ 2.
The left channel is a 3-point moving average of the sawtooth, which has the effect of low-pass filtering. The right channel is the result of the lop object on the sawtooth wave. The cutoff frequency for the low-pass filter is 1 kHz.
The moving average and lop filtering on sawtooth are shown here.