Hey Dude,

there is no mystery as to what a scale is. It is, in its most simple form a way of dividing up an octave.

Like ....
Doe Ray Me Fa So La Tee Doh, from Doe to Doe is an octave (or from any open string on the guitar to a note fretted on the 12th fret of the same string).

Now there are many different ways of dividing up an octave which will give slightly different feels or tonality, like Major is happy and minor is sad.

The most common scale is the diatonic Major scale (Doe to Doe as above) however their are also many other ways of spanning an octave and pentatonic scales are a very convenient for a guitarist. They are also a really good starting point.

Search the tricks section for the reams and reams dedicated to tonality / pents, chromatics, diatonic, arpeggios etc. incorporating Major and (the many different sorts of) minor scale as well as the modes.

Best of luck !