Those are scales. the highlighted notes (aka the guide tones) are notes in that specific chord that give a harmonic pull towards the next chord. generally they are the 3rd and 7th note (that’s what determines what type of chord it may be: major, minor, major-minor, or dominant). they are the most harmonically important notes in the chord since they determine the quality of the chord itself, so make sure they are in perfect tune.
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