The tape has two functions:
You may have to practice the exercises at a slower speed before attempting to play along with the tape. The metronome then, is useful as you can adjust it to the speed you want.
A metronome is a mechanical or electronic device that divides time into equal beats by producing a ticking or bleeping sound. The number of beats per minute is adjustable so that you can vary the speed at which you wish to play a piece of music.
The metronome has three functions: