Andy C. answered 10/24/20
Guitar teacher: Beginner to Intermediate. "Have fun-learn a lot"
The 1,4,5 chord progression is the chord order used in many types of music such as folk, gospel, rock and blues. Here is a quick illustration:
1,4,5 progression in the key of C
1) in the key of C, the scale is C,D,E,F,G,A,B then C as octave.
2) With C being the root note 1 you can see by counting that F is the 4th tone or note, and G is the Fifth.
3) So, this straightforward illustration reveals that the corresponding chords C,F and G make up a 1,4 5 chord progression.
Further study: the deeper understanding of chord structure (the 3 note triad that forms each of the above chords) and chord progressions are defined in detail when the Circle of fifths is studied.