Given the definition above, we would be safe to make the assumption that a Pentatonic Scale is one comprising of five notes. We would also be correct.
Scales are fundamental to music, both in composition and improvisation. Chords within a song are usually made up of notes taken from the scale, and solos or melodies use those same notes.
The pentatonic scales are simplified versions of the full 7-note Major and Minor scales predominantly used within western music. They perform a greater role than just being an easier version of the full scales though, as the notes in the pentatonic scales are arguably much more integral to the scale’s sound.

Once you’ve memorized these scales, try soloing in them – find a backing track in C Major or Minor and just play along.
Then, when you’re happy with what you’ve achieved, think about learning the full Natural Major & Minor Scales.