The V indicates the version of your shoes.
A great example is the New Balance 880v8. The 880 has received multiple updates (v2, v3, v4, v5, v6,v7) with new and improved technologies and stylish colorways.
If you are looking at the complete style number (ex. M860WB7) the letters that follow the number indicate the color code. The 7 indicates the version.
This makes it easy to find the current version of your New Balance favorite!