In any key signature you'll have 8 notes. There are only seven different notes, the first and last will be the same. The distance between these notes is called an octave.
Watch. Heres a C major scale; C D E F G A B C. The first and last notes are the same, and the distance between them is an octave. Get it. Got it. Good.
And God said, 'Let there be rock!'
-And it was good
-And it was good