Welcome to... "Micro-Lesson 273"
The progression is simple in it's harmony, but complex technically /physically in it's use of a multitude of chords from the harmony of, "E Major's," I-IV-V chord degrees.
In the key of, "E Major," the I-IV-V chord changes work out to be, "E, A, and B." Even though this only makes up three chords from the key, we find many different chords applied throughout this progression. The chords are smaller containing on average only 3 notes. But, they move in a busy manner. This is something similar as to how Guitar Players like, "Eddie Van Halen," or, "Jimi Hendrix," played harmonies.
After a pick-up phrase into measure one we find triads used to produce moves through the, "A, E and B," chords. Measure two pushes off of the IV and V chords of, "A and B," to resolve into, "A," for the third measure. The 3rd bar has a cool single-note phrase that highlights notes from the, "E Major," Scale. The single-tone line leads us into measure four where a Plagal Cadence occurs, (IV-I), for return back to the top of the phrase.
Since the chord movements through these busy 3-note shapes happens so quickly, you'll need to practice the physical technique of making them for quite awhile, (especially if these triads are new to you).
Once these chords are well memorized, along with the progressions' order and sequence, begin work at speeding up the riffs tempo. Enjoy!
Micro Lesson 273: "E Major" Classic-Rock Groove