You will learn scales and chords. You will learn how to build chords and voice them on your guitar, and you will learn the basic skills necessary for the transposition of harmonies (this is the fancy musical language for changing the chords of a song into a new key). You will even learn how the chord changes (called "harmonic motion") in pieces creating feelings of tension and relaxation in music and how musicians use this to enhance their performances. In addition, you will learn tips on how we communicate this to our audiences.
You will develop an understanding of the guitar’s history as well as a general history of music and musical styles. You will then use this information to make informed performances; for example, if you were in a Beatles cover band, you would not approach the music in the same way that you would if you were in a Metallica cover band, right? (I'm not saying that mash-up might not sound cool, I'm just trying to make a point here!) You should be thinking in this same way when approaching different pieces by, for example, J.S. Bach (a composer from the Baroque era) or Mozart (a composer from the Classical era).