A chord progression is a succession of chords. Most chord progressions range between 3-8 chords.
Any succession of chords can be a chord progression, for example:
A chord progression like the one above may sound unpleasant because it is a collection of random chords, without a scale relating between them.
If we limit the chord progression to fit within a given scale, it will most likely sound more musical.
Listen to scale based chord progressions: