In scale degrees, what does II or ii represent?

The designation II or ii in scale degrees refers to the supertonic. In the context of a major scale, the supertonic is the second scale degree, which is one whole step above the tonic (the first scale degree). For example, in the C major scale, the tonic is C, and the supertonic is D, which is the second note of the scale.

Understanding the role of the supertonic within the scale is fundamental since it often forms the basis for chord progressions and harmonizations. The supertonic chord is typically a minor chord in a major scale (ii) and is essential for creating movement and tension in music, particularly leading to the dominant (V) chord. This functional role makes the supertonic a significant degree in tonal harmony.