The playhead is the vertical line showing the current playback position in the Tracks area and other time-based windows (such as the Audio Track Editor, Piano Roll Editor, and Score Editor).
With devices equipped with a Touch Bar, you can use the Touch Bar to set the playhead position.
Click a position in the lower half of the ruler.
Shift-click an empty part of the Tracks area at the new position.
Do one of the following:
Click-hold any of the numbers in the Position display and drag vertically.
Double-click either display field, and then enter a new position.
The LCD can display the playhead position in Beats or Time format, or both, depending on which display mode you choose. Beats displays the playhead position in bars, beats, beat divisions, and ticks, while Time displays the playhead position in hours, minutes, seconds, and fractions of a second.
You can edit the individual divisions of the Position display by dragging, or edit the position as a whole by double-clicking and typing.
Click anywhere on the marker while holding down Option.
Tap the Mode button on the left side of the Touch Bar, then tap the Tracks area button 
.
Tap the Touch Bar at the position you want to set the playhead.