Each track is mono (i.e just one signal) but they go into the mixer section, which "sums" each mono track into a one stereo signal (L/R), so when you move the pan control of track 1 (for example) to the left, it sends more of that signal to the Left stereo bus. If the pan control goes all the way to the left, you'll only hear that signal on the left channel of the master (aka Stereo bus) bus. If you pan it 1/2 way between center and completely left, it will sound about twice as loud in the left channel vs. the right channel, so if you're listening on headphones or properly located speakers, it will appear that the sound will be in between completely left and center. Make sense? Now get your Tascam, and start recording! It will become clear once you get going.