The Transport Panel is the part all the way at the bottom of every song window. It contains the elements to controll playback of your entire song. From left to right:

• The CPU meter, that shows how much processor power Reason is taking up. This should stay in green for good performance. Below the CPU meter is the Audio out clipping indicator light. When this burns red the output gain is too high and digital clipping occurs, which is not good. If you see it burning more than occasionally, lower the volume of your track.
• The MIDI zone: the ENABLE button is for switching tempo synchronisation from an external MIDI signal on/off, the SYNC INPUT led indicates if Reason receives any input signal.
• The CLICK button switches a clicktrack on/off, with the knob below it controlling the volume of the clicktrack.
• The tempo and signature of the song. Adjust this from 4/4 to 3/4 if you want to make a waltz :)
• The stop, play, fast rewind, fast forward and record buttons. To record adjustments you make on a device (like turning a knob or switching patterns): make sure the sequencer track of that device is selected for recording, press the record button, than the play button and then make the movements you want to record.
• The current song position
• The loop on/off switch button and the position of the L(eft) and R(ight) locators which mark start and end of the loop.
• The shuffle knob, which controlls how pronounced the shuffle effect is, when turned on on devices like the matrix or Redrum.