What is the significance of the keyword "v/vi" in music theory and how does it relate to chord progressions?

In Music Theory, the keyWord "v/vi" represents the secondary dominant chord of the sixth degree in a major key. It is significant because it creates tension and leads to the vi chord, enhancing the harmonic progression. This chord is often used to add color and interest to chord progressions by temporarily shifting the tonal center before resolving back to the original key.