My guitar has this weird reverberating sound after I strum a chord? Is this normal?
What you're hearing is the peaks and valleys of the sound waves misaligning. If your guitar is slightly out of tune and you play the same "note" in two locations (like "A" on your open "A string" + "A" at the 5th fret of your "E string") you will hear this wobble more clearly. Some may also describe it as a Leslie effect (rotating speaker cabinet). As you re-tune the strings more accurately, you'll notice the wobbles / reverberations start to align until they effectively disappear.
Unfortunately due to the nature of Equal Temperament and the guitar, some chords will do this more than others, even when you are "in tune." But there's nothing wrong with your instrument. In fact, some find this sound is desirable :)