Chords are built from scales. The most basic music chord is built using three notes and is called a triad. In jazz music they use a lot of four or more note chords. If you play two successive note together they sound dissonant. Therefore chords are built in thirds or every other note. For example, the first scale you should learn is the C Major scale. It is the notes C,D,E,F,G,A,B and C again (the same note 1 octave higher). Triad chords in the C Major scale are C Major (CEG), D minor (DFA), E minor (EGB), F Major (FAC), G Major (GBD), A minor (ACE), B diminished (BDF). I recommend when you first are learning new terms and material that you just accept it and not try to understand all of it at once. Eventually you will begin to understand why and things will make sense to you better. Music is endlessly complex and dynamic so relax and enjoy that there is always new things to learn. Learn the C major scale all over the guitar fret board and all the triads. By doing this you will have a solid foundation and will be able to learn all the other scales and modes easily and understand the theory involved.