@MonsterYT_DaGamer here are the basics.
Melodies:
Melody is a linear sequence of notes the listener hears as a single entity. The melody of a song is the foreground to the backing elements and is a combination of pitch and rhythm. Sequences of notes that comprise melody are musically satisfying and are often the most memorable part of a song.
Harmony:
Harmony occurs any time two or more differently pitched notes are played at the same time. Harmony can refer to the arrangement of the individual pitches in a chord as well as the overall chord structure of a piece of music.
Rhythm:
Rhythm is the way that music is systematically divided into beats that repeat a specific number of times within a bar at a collectively understood speed or tempo.