Here, the Roman numerals tell you that the chords are Bm (hence ii is lowercse), E and A in the key of A major. Finally, here's a simple Ionian solo. The first four bars use chord tones (notes ...
As a result of this, the guitar parts are often played with slightly different chord inversions, or a reduced number of notes played to free up space for the keys. This 4 string take on a Major 7 ...