I would like to use this scale to start improvising on an acoustic guitar. I understand the shape on the neck, but I want to increase my knowledge and ask you how is it constructed. Thank you for help!
Well, you can think of it in one of two ways.
Interpretation 1: Relation to popular music: Popular music tends to be based on the major scale, which you've probably encountered. The major scale has a whole, whole, half, whole, whole, whole, half structure. I'll provide two examples because music theory books always use C major and I think that stunts learning:
C major: C, D, E, F, G, A, B, C
D major: D, E, F#, G, A, B, C#, D
The pentatonic scale is like the major scale but with the fourth and seventh note removed. This produces a much more consonant scale with no half-steps:
C pentatonic major: C, D, E, G, A, C
D pentatonic major: D, E, F#, A, B, D
Interpretation 2: an endless cycle of fifths: You may have learned a bit about intervals which is just a word for any distance between any two notes. Intervals are actually pretty important in understanding scales and chords. Without getting too technical, the most consant interval (besides an octave, which is just the same note repeated, but higher) is the perfect fifth. Experience will prove it. The perfect fifth is in almost every chord, almost every scale, and even can be heard as a harmonic note. Whenever any note is played, its perfect fifth rings vaguely in the background. The pentatonic scale can also be generated by building a series of perfect fifths and then putting them in order of lowest to highest. Let's try C:
Series of perfect fifths from C: C, G, D, A, E
Series of perfect fifths from D: D, A, E, B, F#
Put them back in order from lowest to highest and you have the same two pentatonic scales as above.
Now, as for how to use the scales: in the most simple way, you can use the scale whenever you're in the corresponding key. You can use a C major pentatonic scale to improvise whenever you're in a C major key. But you can also use it to improvise in some other keys that have the same notes. For instance, since neither the key of G nor the key of F has a note conflicting with the C major pentatonic (i.e., all of the notes of the C major pentatonic can be found in those keys as well), you can use it to improvise in those keys too. But the effect may a bit weirder.
And just to give you a little bit of scale-jutsu: the fact that the pentatonic scale has only 5 notes means that some more advanced improvisers like to use it to devise creative and interesting ways to play over complicated harmony. But figuring out how to do that is more like doing homework than playing music, at least at first.
The scale has five unique pitches (hence the name) and they are separated by the intervals: W–W–m3–W–m3 where W is a whole step and m3 is a minor third (3 frets). The last m3 takes you to the starting pitch an octave higher. Example:
It's taken from the full major scale. Two notes are omitted - the 4th and 7th. So in C, for instance, the notes C,D,E,G and A are used. F and B are not.Those notes are quite likely to clash with chords played in that key, unless the player knows what to do.The simple reason being, no two notes are very close to each other (at least two frets(a tone)). Yes, sometimes a note you'll play won't sound brilliant over a chord, but nothing will sound horrific.
The same notes are also used to solo over A minor, as they are relatives to each other.
There are several shapes that work well on guitar, 5 at the last count, so have a try at finding the others, as it somehow makes you play differently - using only one position means that slides up and down can only be between certain notes (on the same string!), so knowing the shapes either side of the one you already have will greatly increase your propensity to do great solos.