An octave is an interval between one musical pitch and another with half or double its frequency.
In other words, an octave is the same note at a higher or lower pitch.
Try playing these octaves:
You may be wondering how you can play octaves without sounding the note on the string in between. The solution is easy. Just lay your first across the dead string- just enough to deaden it. Technically you’re muting that string.
Once you have to 2-octave shapes down, practice taking octaves all over the fretboard!