The commenter is telling you that he or she made your image a favorite (though Facebook also starts with F so I'm never sure unless I check - you can see whether an image has been shared through FB or, by going to your Favorites, favorited and by whom), liked it (you can't see that really except the number goes up and who keeps track?). V may mean nothing, especially in combination with l - liking an image used to be called "voting" and lots of people still say "v" when they mean "like". But if you have entered the image in a contest, it MAY mean that they actually voted for it there. You may be able to tell that, too. Fact is, most of this stuff is pretty meaningless. A comment is already a great thing to get. I almost always "like" an image that I comment on - not just like it but click the like icon - and sometimes make it a Favorite, too, and I never add these little letters to my comments.