brummy... that's e5, and B5add11/E i think.
parallel 5ths and 8ths (a.k.a. octaves) happen -basically- when you move from one chord with a 5th (or octave) in it to another chord with a 5th (or octave) in it, and then to another etc. So, on a guitar, if you're keeping the same in the left hand shape and just moving up and down the neck, you're moving in parallel. see? =) as the above forum says, it's non-essential knowledge.