The V65/V chord, also known as the V 6/5 of V, is a type of secondary dominant chord that functions to tonicize the dominant chord (V) of the current key. This chord is a first inversion dominant seventh chord built on the fifth scale degree of the dominant chord's key, creating a temporary shift in tonal center. By using this chord, composers can add tension and create a stronger resolution to the dominant chord, enhancing the overall harmonic progression.