The key to understanding all the chord progression, scale, mode, modulation jargon is to train yourself to listen to every note being played at any given moment, which believe it or not is entirely possible. It doesn't matter how dissonant something is for a brief time, first identify the sound of the chord and in the next instant identify the note in the bass to get an idea of the chord in the scale and its inversion. The actual scale or mode is usually identified easily enough in the melody. If this sounds like too much already, you may not want to study music theory as it may not be something you can apply to in listening to or writing music. Most great musicians would have no idea what I just said, meaning understanding music really isn't important for enjoying it or writing it.